Preparation of lead-coated sweet sorghum stalk-based carbon material and its electrochemical performance

Preparation of lead-coated sweet sorghum stalk-based carbon material and its electrochemical performance | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Preparation of lead-coated sweet sorghum stalk-based carbon material and its electrochemical performance Qiuqun Liang, Xiaoqi Lan, Zheng Liu, Junjie Ma, Guo-Cheng Han, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4881412/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Sweet sorghum stalk can be used to prepare carbon materials and used in lead carbon battery negative materials. In this work, the sweet sorghum stalk was pretreated with 5 wt.% H 3 PO 4 , after heated at 550℃ for 105 min, lead-coated sweet sorghum stalk-based carbon materials were prepared by the solvent method, and their electrochemical performance were measured by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), as well as BET test, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray powder diffraction spectrum (XRD) methods. The negative electrode materials contained lead-coated sweet sorghum stalk-based carbon material and physical grinding compared material were assembled into simulated lead-carbon batteries, the charge-discharge tester was used to test their first charge-discharge curves and cycle life curves, the first discharge specific capacity of two kinds materials were 73.0 mAh/g and 57.24 mAh/h, with 71.8% and 57.5% of capacity retention ratios after 150 cycles, respectively, shown that the simulated lead-carbon battery with new prepared carbon material exhibits better electrochemical performance. Sweet sorghum stalk carbon material Coated Lead carbon battery Negative material Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Introduction Lead-acid batteries play an important role in the global rechargeable battery market due to their low cost, mature manufacturing process and recyclability, and are widely used in automotive and industrial fields[ 1 , 2 , 3 , 4 ], especially in the field of low-speed electric vehicle applications have great advantages[ 5 , 6 , 7 ]. However, when the lead-acid battery is in a partially charged state with high rate charge and discharge mode, the negative electrode PbSO 4 cannot be reduced to sponge lead in time. As the discharge state continues, large particles of PbSO 4 will gradually accumulate on the surface of the negative electrode, forming a layer of dense PbSO 4 crystals, resulting in a decrease in the area of the negative electrode active substances. It affects the charging and discharging efficiency and the cycle life of lead-acid batteries [ 8 , 9 , 10 , 11 ], thus limiting the application of lead-acid batteries in new energy vehicles [ 12 , 13 ]. In order to solve this problem, a carbon material is added to the negative electrode material of the lead-acid battery, and the lead-carbon battery is formed[ 14 ]. As a lead carbon battery developed on the basis of lead-acid batteries, it is a new type of battery that combines the high energy density of lead-acid batteries with the high power density of supercapacitors, it is widely used in the field of device energy storage and power battery, and the lead carbon battery is similar to the traditional lead-acid battery production process, and the industrialization is relatively easy. The addition of carbon material to the negative electrode of the lead carbon battery can solve the irreversible sulfation of the battery under high-rate charge and discharge conditions to a certain extent, thereby prolonging the service life of the lead carbon battery[ 15 , 16 ]. The main reason is the added carbon material, the conductive network that can be built in the negative electrode material, the increase of the electric double layer capacitance performance, and the increase of reactive sites[ 17 , 18 , 19 ]. The addition of carbon materials has also brought certain problems, for example, there is an obvious phase interface between carbon material and negative active material, this phenomenon will cause the battery to run interrupted under high-rate charge and discharge conditions for a long time[ 20 ]. In addition, due to the addition of the carbon material, the hydrogen evolution overpotential of the negative electrode is reduced, a hydrogen evolution phenomenon is generated during the charging process, and after a plurality of cycles, the electrolyte loss can be caused, and the sulfuric acid concentration of the electrolyte increases, further causing the sulphation of the negative electrode to be intensified[21,22.23]. Therefore, it is of great significance to study and solve the above problems encountered in lead-carbon batteries. Naresh and co-workers[ 23 ] used industrial asphalt as a carbon source to combine with SnO 2 under high temperature conditions, and finally prepared carbon-coated SnO 2 materials. The results show that the carbon layer can improve the conductivity and charge storage performance of the anode active material, thereby improving the capacity and cycle performance of the battery, at the same time, C/SnO 2 occupies the pores of the negative active material, suppresses the growth of PbSO 4 and reduces the precipitation of hydrogen. When the composite is added to the lead-acid battery, the charging rate of the composite under the condition of high rate partial charge is 300% higher than that of the traditional lead-acid battery. Zhang and co-workers[ 24 ] used rice husk-derived ultra-large micron-sized porous carbon and commercial activated carbon as composite electrode materials for lead-carbon batteries, tested under high-rate partially charged state (HRPSoC) conditions, the composite electrode with rice husk derived carbon has high coulombic efficiency (close to 100%) and long cycle life during operation, this is because commercial activated carbon has smaller micropore structure and higher specific surface area than rice husk derived carbon, when a large number of commercial activated carbon is added, lead-carbon batteries have obvious hydrogen evolution, which leads to capacity attenuation and coulomb efficiency reduction. Lead-carbon composites with rice husk derived carbon provide a larger carbon surface for electrodeposition of lead because of the rough surface of rice husk derived carbon, a stable structure is formed in the process of charge and discharge, so it has stable capacity and coulomb efficiency. Zhang and co-workers[ 25 ] prepared a graphene-like two-dimensional carbon/PbSO 4 composite by simple chemical vapor deposition and ion exchange, the results show that the composite can effectively improve the electrical conductivity and ionic conductivity of the material, and can effectively inhibit the irreversible sulfation of the negative electrode during the operation of HRPSoC, in addition, PbSO 4 deposited on the layered carbon can uniformly mix the carbon additive with the active material, and can inhibit the occurrence of hydrogen evolution to a certain extent, thereby improving the high rate charge and discharge performance of the lead-acid battery. Energy grass is a general term for annual tall herbaceous plants, the ideal energy grass species mainly include sweet sorghum, switchgrass, and pennisetum[ 26 ]. Sweet sorghum is the most widely used energy grass in the energy field, India, Australia and other countries have carried out research on the production of ethanol fuel from sweet sorghum[ 27 ], compared with other cash crops, sweet sorghum has great advantages in terms of yield and economic benefits[ 28 ]. In addition, sweet sorghum is widely used in wine making[ 29 ], papermaking[ 30 ], and sugar making[ 31 ]. Khalil and co-workers[ 32 ] used sweet sorghum stalk as carbon source and impregnated with activator ZnCl 2 to prepare carbon materials with different surface areas at different pyrolysis temperatures to adsorb harmful cationic dyes and achieved good adsorption. Xu and co-workers[ 33 ]used sweet sorghum stalk as carbon source, flake carbon structure was prepared by carbonation and applied to high energy lithium ion capacitors, after 5000 cycles at 10 A g − 1 current, the capacity retention rate is 66%, which has good power performance. In order to improve the comprehensive utilization of energy grass, waste sweet sorghum stalk was used as carbon source to prepare lead-coated sweet sorghum stalk-based carbon materials by solvent method in this paper. The bonding structure, thermal stability and morphology of the sweet sorghum stalks after pretreatment were analyzed by infrared light spectrum(IR), thermogravimetric curve(TG) and scanning electron microscope(SEM), the graphitization degree of the sweet sorghum stalk-based carbon materials were analyzed by Raman spectroscopy (Raman), the electrochemical properties of lead-coated sweet sorghum stalk-based carbon materials were analyzed by cyclic voltammetric (CV) and electrochemical AC impedance method(EIS), then, the energy dispersive spectroscopy (EDS), X-ray powder diffraction spectrum(XRD), and BET curve were used to compare and analyze the morphology, element content, phase structure, specific surface area and pore size distribution of the pretreated sweet sorghum stalk, the prepared sweet sorghum stalk-based carbon material, and the prepared lead-coated the sweet sorghum stalk-based carbon material under the optimal conditions. The self-made lead-coated carbon material was mixed with a battery auxiliary to prepare a negative electrode material, and finally assembled into a simulated lead carbon battery, the first discharge performance and cycle performance of the battery were tested and analyzed. Experimental part Materials and reagents The sweet sorghum stalk was provided from Hengshui Farm in Hebei Province. The chemical reagents used were purchased from Aladdin Reagent (Shanghai Co., Ltd.), Xilong chemical co., Ltd., Chaowei Battery Company and Tianjin Guangfu Fine Chemical Research Institute. The lead calcium alloy anode plates were obtained from Baoding Meilun Nonferrous Metal Co., Ltd., lead dioxide cathode plates were acquired from Baoji Changli Special Metal Co., Ltd., AGM separators were purchased from Yingkou Zhongjie Shida Separator Co., Ltd. The laboratory water was homemade distilled water. Pretreatment of sweet sorghum stalk The sweet sorghum stalk was washed with distilled water, then was placed in a blast drying box, and dried at 60°C for 12 h, and then was cut into small pieces of 1 cm with scissors. The sweet sorghum stalk was soaked in the prepared 5 wt.% H 3 PO 4 solution and treated at 50°C for 24 h. The treated sweet sorghum stalk was separated, rinsed with distilled water until the material was neutral, and dried in an oven at 90°C for 24 h. Preparation of lead-coated sweet sorghum stalk carbon material The dried sweet sorghum stalk had been placed in a closed grinding mill for grinding and grounded into a 300–400 mesh powder. 2.0 g sweet sorghum stalk powder had been weighed and transferred into a quartz boat. The quartz boat had been placed in a vacuum tube furnace and heated at 550°C for 105 min under an argon atmosphere, the flow rate of the argon gas had been controlled to 100 mL/min, the heating rate was 5°C/min, and the temperature was naturally cooled to room temperature, that was, a sweet sorghum stalk-based carbon material was obtained. 3.31 g of Pb(NO 3 ) 2 had been dissolved in 50 mL of distilled water, 1.89 g of NaBH 4 had been dissolved in 50 mL of distilled water, and 0.01 g of sweet sorghum stalk-based carbon material had been dissolved in 50 mL of absolute ethanol. The Pb(NO 3 ) 2 solution had been placed in a flask, and added 25 mL of ethanol solution of sweet sorghum stalk-based carbon material while stirring for 1 h. The reducing agent NaBH 4 solution had been added dropwise in an ice water bath and stirred for 45 min until a black precipitate (Pb) was formed. The black precipitate had been filtered, and the remaining 25 mL of a sweet sorghum-based carbon material ethanol solution had been added to the filtrate, stirred for another 45 min, and then black precipitate was separated again. The black precipitate had been washed several times with ethanol and water and dried in a vacuum oven at 50°C for 8 h to obtain a lead-coated carbon material. Preparation of positive and negative materials for lead carbon batteries The 0.5 g lead-coated sweet sorghum stalk-based carbon material, negative active material(lead oxide 3 g), conductive agent(acetylene black 0.15 g), expander (humic acid 0.09 g, barium sulfate 1.8 g)and antioxidant (barium stearate 0.9 g) had been uniform mixed, grinded in an agate mortar for 20 min, after several powders are thoroughly mixed, transfer the material to a 250 mL beaker, then added 6 mL of 60% polytetrafluoroethylene (PTFE) emulsion, a certain amount of distilled water, and 6 mL of 1.38 g/cm 3 sulfuric acid solution, mechanically stirred until a paste substance was formed, that was, a lead carbon battery negative material (lead paste) was obtained. The positive active material(lead dioxide 10 g, lead oxide 3 g), conductive agent(acetylene black 0.15 g), antioxidant (barium stearate 0.9 g) and barium sulfate (1.8 g) had been uniform mixed, grinded in an agate mortar for 20 min, after several powders had been thoroughly mixed, transfer the material to a 250 mL beaker, then added 6 mL of 60% polytetrafluoroethylene (PTFE) emulsion, a certain amount of distilled water, and 6 mL of 1.38 g/cm 3 sulfuric acid solution, mechanically stirred until a paste substance was formed, that was, a lead carbon battery positive material was obtained. The lead carbon battery negative and positive materials had been respectively applied to the negative and positive slab lattice, uniformly coated and compacted, and then the electrode plates had been placed in an oven at 60°C for 12 h to obtain the positive and negative electrodes of the lead carbon battery. Material characterization The TG curves and IR spectra of the pretreated sweet sorghum stalk were determined by the thermogravimetric analyzer of SDT-Q600 of American TA Company and the Fourier transform infrared spectrometer of Thermo Fisher iS10 type by American Thermo Fisher Company, the SU5000-type field emission scanning electron microscope of Hitachi(Japan) was used to test the surface characteristics of the pretreated sweet sorghum stalk and the morphology of the lead-coated sweet sorghum stalk-based carbon material, the test conditions were voltage 3kV, emission current 10100 nA, working distance 6000 µm. The elemental content of the lead-coated sweet sorghum stalk-based carbon material was determined by the XFlash6l10 Bruker type energy spectrum system of the company, test conditions were as follows: working distance was 5–40 mm, spatial resolution was 0.5 µm, angular resolution was 0.50. The Raman spectra of carbon materials prepared at different activation temperatures were determined by Inrivia laser Raman spectrometer from Renishaw, UK, the laser wavelength was 514 nm, the graphitization degree of carbon materials was measured by analyzing the intensity ratios of D and G peaks of carbon materials, the phase composition and phase structure of lead-coated sweet sorghum stalk-based carbon material were characterized by X'Pert3-Power X-ray powder diffraction apparatus of Panaco, Netherlands. The test conditions were as follows: test voltage was 40kv, current was 40 mA, Cu(Kα)target, λ = 1.54426, scan rate was 16⁰ min − 1 , scan range was 10 ~ 90⁰, the pore volume, pore size and specific surface area of the lead-coated sweet sorghum stalk-based carbon material were analyzed by V-Sorb 2800TP specific surface adsorption instrument of Beijing Jine Spectrum Technology Co., Ltd. Electrochemical performance test The CHI760 electrochemical workstation(Shanghai Chenhua Instrument Co., Ltd.) was used, and the negative electrode of the self-made lead carbon battery was used as the working electrode, the reference electrode of the calomel electrode was used as the reference electrode, the platinum wire electrode was used as the auxiliary electrode, and the sulfuric acid solution of 1.05 g/mL was used as the electrolyte, the three-electrode system was subjected to CV and EIS. CV conditions were as follows: scan potential interval was − 1.2 ~ 0.1 V, scan rate was 0.01 mV/s; EIS test parameter was set to 0.5 ~ 10000 Hz, initial potential was open circuit potential, and amplitude was 5 mV. The specific capacitance of the carbon material electrode can be calculated according to the formula(1): $$\:\text{C}=\frac{1}{mv({V}_{c}-{V}_{a})}{\int\:}_{{V}_{a}}^{{V}_{c}}{I}_{V}{d}_{V}$$ 1 where C is the specific capacitance (F g − 1 ), m is the mass (g) of the active material on the electrode, and v is the scanning rate (V s − 1 ), (V c -V a ) is the potential range (V) during discharge, and I v is the response current density (A cm − 2 )[ 34 ]. The electrochemical impedance spectroscopy was analyzed by Z-View software, in which Rs is the material resistance of the negative electrode, R1 is the solution resistance, C1 is the solution capacitance, and CPE is the electrode/solution interface capacitance. The lead carbon battery was assembled according to the positive and negative plates prepared by 2.4 and the AGM diaphragm, the electrolyte was 1.14 g/mL sulfuric acid solution, and using CT-3008-5V-20A Neware battery test system, the first cycle charge and discharge performance test of the assembled simulated lead carbon battery was carried out by constant current circulating charge and discharge method, the control current was 750 mA and the cut-off voltage was 1.70 V. At the same time, the cycle life of the simulated battery was measured, and the electrochemical cycle stability of the carbon material was analyzed. Results and discussion Pretreatment optimization of sweet sorghum stalk Sweet sorghum stalk was pretreated with 5 wt.% H 3 PO 4 solution, mixed acid solution (36 wt.% CH 3 COOH and 68 wt.% HNO 3 solution), 10 wt.% NH 3 ∙H 2 O solution and 5 wt.% NaOH solution. The pretreated sweet sorghum stalk was measured by IR, TG and SEM as shown in Fig. 1 to Fig. 4 , respectively. (Fig. 1 ) Classically, Fig. 1 is an IR spectrum of four different pre-treated sweet sorghum stalk. The absorption peaks around 3340 cm − 1 , 2920 cm − 1 , 1735 cm − 1 , 1590 cm − 1 , 1430 cm − 1 , and 1050 cm − 1 can be attributed to C-H stretching vibration, C-H stretching vibration of methyl and methylene, C = O stretching vibration of polyxylose, C = O stretching vibration of lignin, C = O stretching vibration of hemicellulose, and C = O stretching vibration of cellulose and hemicellulose, respectively. Among the above four pretreatment conditions, the treatment of 5 wt.% H 3 PO 4 is more thorough in the decomposition of polyxylose and hemicellulose. In the mixed acid, due to the addition of HNO 3 , the decomposition of poly-xylose and hemicellulose by CH 3 COOH has a certain hindrance effect. Therefore, a C = O stretching vibration peak in polyxylose and hemicellulose appears. When the sweet sorghum stalk treated with 10 wt.% NH 3 ∙H 2 O and 5 wt.% NaOH, the characteristic absorption peaks of lignin and cellulose both appeared, which indicated that the degree of cellulose decomposition of lignin in sweet sorghum stalk was small. However, the sweet sorghum stalk treated with 5 wt.% NaOH, the characteristic absorption peak of hemicellulose appeared. Figure 2 is TG curves of sweet sorghum stalk with different pretreatment. (Fig. 2 ) It can be seen from Fig. 2 that a certain amount of weight loss occurs in the vicinity of 70°C ~ 80°C. This phenomenon occurs because the sweet sorghum stalk contains a certain amount of adsorbed water, and with the increase of temperature, the water in the sweet sorghum stalk is volatilized, that is, the weight loss in the interval of 70°C ~ 80°C is the weight loss caused by the thermal evaporation of water. After 80°C, the TG curves entered the platform, indicating that the sample was in a thermally stable state. 5 wt.% H 3 PO 4 treated sample, the TG curves declined at 150℃, and the TG curves appeared on the platform at 800℃, and the residual rate of the sample was 10%, the weight loss temperature of the other pretreated samples was about 200℃, and the platform temperature of TG curve was lower than that of 5 wt.% H 3 PO 4 treatment samples, and the residual rate of the samples were also low. Thermogravimetric analysis showed that the carbon material with high yield could be obtained by treating the sample with 5 wt.% H 3 PO 4 . This may be due to the fact that phosphate can effectively dissolve the pectin in sweet sorghum stalk, while lignin and cellulose dissolve less in sweet sorghum stalk[ 35 ]. The surface morphology of the treated sweet sorghum stalk was characterized, the results are shown in Fig. 3 . (Fig. 3 ) Figure 3 (a) and (b) showed that the sweet sorghum stalk tubular bundle after phosphoric acid treatment is more obvious, and the impurities of small particles on the surface are less. Figure 3 (c) and (d) showed that the tubular bundle of the sweet sorghum stalk treated by the mixed acid treatment has a large degree of damage and a rough surface, which may be caused by a certain depolymerization of cellulose. Figure 3 (e) and (f) showed that the tubular bundle of the sweet sorghum stalk treated with NH 3 ∙H 2 O has a large degree of damage and a large distribution of surface particles, which indicates that the surface-adhered impurities have not been completely removed. Figure 3 (g) and (h) illustrated that the surface of the sweet sorghum stalk treated with NaOH is rougher. Therefore, the optimal pretreatment method for determining the sweet sorghum stalk is to use 5 wt.% H 3 PO 4 treatment by analysis of the above three characterization methods. Optimization of preparation conditions for lead-coated sweet sorghum stalk-based carbon materials (1)Temperature optimization Temperature is a very important factor for material preparation. The obtained sweet sorghum stalk-based carbon material samples were subjected to Raman test according to the method of "Preparation of positive and negative materials for lead carbon batteries ", as shown in the Fig. 4 , calculated the R value list it in Table 1 . Table 1 R value of sweet sorghum stalk-based carbon materials at different temperatures. Preparation temperature of sweet sorghum stalk-based carbon material/°C R value Crystallite size (La)/nm 400 0.8433 5.16 450 0.8269 5.26 500 0.7694 5.65 550 0.7427 5.86 600 0.8539 5.09 650 0.8572 5.07 700 0.8623 5.04 750 0.8679 5.01 800 0.8992 4.84 850 0.9188 4.73 900 0.9394 4.63 (Fig. 4 and Table 1 ) It can be seen from Fig. 4 that with different preparation temperature, the peak D peak of prepared sweet sorghum stalk-based carbon material appears in 1360 cm − 1 , which belongs to A 1g mode, which is the Raman activity of crystallization boundary region in graphite of sweet sorghum stalk-based carbon materials, contribute to the crystallization size effect. The G peak appears near 1580 cm − 1 and belongs to the E 2g mode, it appears in all carbon fiber spectra, the presence of the 1580 cm − 1 peak is the basis of the graphite structure of the sweet sorghum stalk-based carbon materials[ 36 ]. The R ratios of I D /I G are listed in Table 1 . It can be seen that the carbon material with the highest graphitization degree can be obtained by heating at 550℃, so 550℃ is the most suitable preparation temperature. (2)Carbonization time optimization The carbonization experiment was carried out at 550°C in accordance with the method of "Preparation of positive and negative materials for lead carbon batteries ", and the obtained samples of the sweet sorghum stalk-based carbon material was subjected to Raman spectra and BET test. The results are shown in Fig. 5 to Fig. 8 , and the R value was calculated as shown in Table 2 . Table 2 R value of sweet sorghum stalk-based carbon materials at different carbonization times. Carbonization time / min R value Crystallite size (La)/nm 30 0.8783 4.9527 45 0.9296 4.6794 60 0.8755 4.9686 75 0.9505 4.5765 90 0.9159 4.7494 105 0.8643 5.0329 120 0.9015 4.8253 (Fig. 5 and Table 2 ) It can be seen from Fig. 5 and Table 2 that the Raman spectrum R values of the sweet sorghum stalk-based carbon material samples prepared at different carbonization time are quite different, and the R value was calculated, obtaining that when the preparation time was 105 min, the graphitization degree of the sweet sorghum stalk-based carbon material was the highest. Figure 6 is a nitrogen adsorption-desorption curve diagram and a pore size distribution diagram (insert) of the sweet sorghum stalk-based carbon material at different carbonization times, and the data obtained in the figure are summarized and listed in Table 3 . Table 3 Specific surface area and pore size of sweet sorghum stalk-based carbon materials under different carbonization times. Carbonization time / min Specific surface area / (m 2 /g) Pore width / nm 30 233.131 27.395 45 258.428 2.086 60 280.083 1.956 75 307.004 2.274 90 313.093 2.086 105 411.422 2.086 120 346.918 2.086 (Fig. 6 andTable 3) It can be seen from Table 3 that as the carbonization time increases, the specific surface area of the sweet sorghum stalk-based carbon material increase first and then decrease. When the carbonization time is 105 min, the specific surface area is the highest, which is 411.422 m 2 /g. It can be seen from Fig. 6 that the sweet sorghum stalk-based carbon materials have a certain degree of hysteresis loop with different carbonization time, indicating that the carbon material contain a partial mesoporous structure 37 , at the same time, the average pore diameter of the sweet sorghum stalk-based carbon materials were about 2 nm except for 27.393 nm with the carbonization time of 30 min. The optimum carbonization time of the sweet sorghum stalk-based carbon material was determined by Raman spectra and nitrogen adsorption-desorption curve diagram to be 105 min. (3)Reduction time optimization According to the step in "Preparation of positive and negative materials for lead carbon batteries ", the other conditions were kept same, and studied the time of sodium borohydride to reduce the lead nitrate ethanol solution of carbonaceous materials. The EIS curves and CV curves of the lead-coated sweet sorghum stalk-based carbon materials at different reduction times were tested. The results are shown in Fig. 7 and Fig. 8 , and the data obtained in the figures are obtained in Table 4 to 6 . The equivalent circuit is shown in the inset of Fig. 7 . Table 4 EIS spectrum datas of lead-coated sweet sorghum stalk-based carbon materials at different reduction times after fitting. Immersion time / min Rs R1 C1 R2 CPE-T CPE-P 15 0.49433 0.021665 0.010921 15.28 0.53296 0.042484 30 1.056 0.28147 0.00060078 122.5 0.018089 0.59118 45 0.34654 0.15766 0.013518 82.3 0.06145 0.50419 60 0.8946 1.305 0.00018223 1042 0.01777 0.46238 75 0.40793 0.78361 0.016056 19.57 0.097772 0.44064 Table 5 CV datas of lead-coated sweet sorghum stalk-based carbon materials at different reduction times. Immersion time / min Area enclosed by graphics / cm 2 Specific capacitance / F g − 1 15 0.2837 7.8806 30 0.3125 8.6806 45 0.3767 10.4639 60 0.2438 6.7722 75 0.3073 8.5361 Table 6 Element contents of three materials(sweet sorghum stalk, sweet sorghum stalk-based carbon material, lead-coated sweet sorghum stalk-based carbon material). Materialsꞌ name Proportion of each element C / % O / % Pb / % Na / % sweet sorghum stalk 53.85 45.75 0 0 sweet sorghum stalk-based carbon material 74.34 21.87 0 0 lead-coated sweet sorghum stalk-based carbon material 9.26 17.64 71.42 1.68 (Fig. 7 and Table 4 ) It can be seen from Fig. 7 that the EIS spectrum has three main parts, the first part is the semicircle in the high frequency region, which is the ohmic impedance of the solution, the second part is the straight line in the medium frequency region, which mainly represents the diffusion resistance of electrolyte ions in the electrode gap, and the third part is the capacitance reactance in the low frequency region, which mainly represents the charge transfer impedance[ 38 , 20 ]. It can be seen from Table 4 that comparing the lead-coated sweet sorghum stalk-based carbon materials with different reduction time, it is found that the Rs of the lead-coated sweet sorghum stalk-based carbon materials prepared with a reduction time of 45 min is the smallest. The CV curves of lead-coated carbon materials at different reduction time were tested, the results were shown in Fig. 8 , and the area data were listed in Table 5 . (Fig. 8 and Table 5 ) It can be concluded from Fig. 8 that there is a pair of redox peaks on each curve, which indicates that the reaction has obvious capacitance characteristics, which is related to the redox reaction of Pb 2+ /Pb pairs in solution. In addition, depending on the immersion time, the positions of the redox peaks on each CV curves are different, and the peak current intensities are also different. It can be seen from Table 5 that the lead-coated sweet sorghum stalk-based carbon materials prepared at a reduction time of 45 min has the largest specific capacitance. This is because the reduction time is too long, and the addition of Pb(NO 3 ) 2 can be completely reduced to lead, and the carbon material is added in an amount, and the generated lead is greatly excessive, except for the carbon material, the remaining lead will agglomerate on the surface of the carbon material, hindering the formation of the lead-carbon conductive network channel and reducing the effect of the carbon material, so the peak current of the electric double layer is reduced and the specific capacitance is reduced. Coating lead particles on the surface of carbon materials can inhibit the formation of large size PbSO 4 , improve the conductivity, and inhibit the precipitation of hydrogen to a certain extent, thus improving the Faraday redox reaction and capacitance performance of the battery. The lead-coated sweet sorghum stalk-based carbon material with reaction time of 45 min has smaller migration resistance and larger specific capacitance. The migration resistance has an important influence on the electron-ion exchange process in the electrochemical reaction of negative electrode materials, the increase of specific capacitance can reduce the damage caused by high current charge and discharge to the electrode plate of lead carbon battery, in addition, it can provide partial electric double layer capacitors, which can increase the capacitance performance of lead carbon batteries. Characterization of materials (1) SEM analysis Figure 9 shows SEM of 5 wt.% H 3 PO 4 pretreated sweet sorghum stalk (a), the sweet sorghum stalk-based carbon material (b), and the lead-coated sweet sorghum stalk-based carbon material (c). (Fig. 9 ) After 5 wt.% H 3 PO 4 pretreatment, the sweet sorghum stalk still maintains a good tubular bundle structure Fig. 9 (a), indicating that lignin and cellulose are not destroyed, it provides the basis for the preparation of sweet sorghum stalk-based carbon material and lead-coated sweet sorghum stalk-based carbon material. It can be seen that the sweet sorghum stalk-based carbon material preserves the complete channel structure and improves the surface wettability of carbon materials and provides a better carbon substrate for lead coating in Fig. 9 (b). Interesting, it can be clearly seen that the core-shell coating structure with carbon as the core and lead as the shell in Fig. 9 (c), and the formed cladding structure has the characteristics of loose texture and porous, which has great correlation for the formation of electrochemical channels. (2) EDS Analysis Figure 10 is an EDS spectrum of the pretreated sweet sorghum stalk (a), sweet sorghum stalk-based carbon material (b), and lead-coated sweet sorghum stalk-based carbon material (c), and the data of each element are listed in Table 6 . (Fig. 10 and Table 6 ) It can be seen that the characteristic peaks of C and O appear in the scanning interval in Fig. 10 (a), the carbon proportion of the sweet sorghum stalk is 53.85%, the oxygen proportion is 45.75%. From Fig. 10 (b), the peak intensity of the carbon element is significantly enhanced, the carbon proportion reach to 74.34%, and the oxygen proportion is 21.87%. After doping Pb, not only the characteristic peaks of C, Pb, and O elements, but also Na element appears, which may be due to the NaBH 4 reaction residue during the preparation process, the carbon content of the lead-coated sweet sorghum stalk-based carbon material is 9.26%, the oxygen content is 17.64%, and the lead content is as high as 71.42%. This indicates that lead is basically coated on the surface of the carbon material[ 39 , 40 ], it can continue to provide a pseudocapacitance effect for charging and discharging, and weaken the damage to the negative electrode during charging and discharging. (3) BET analysis Figure 11 is nitrogen adsorption-desorption test diagram and pore diameter distribution diagram of three materials (insert) of the pre-treated sweet sorghum stalk(a), sweet sorghum stalk-based carbon material(b), and lead-coated sweet sorghum stalk-based carbon material(c), and the specific surface area and average pore diameter of the three materials are listed in Table 7 . Table 7 Specific surface area and pore size of carbon material of three materials(sweet sorghum stalk, sweet sorghum stalk-based carbon material, lead-coated sweet sorghum stalk-based carbon material). Materialsꞌ name Specific surface area / (m 2 /g) Pore width / nm sweet sorghum stalk 13.0337 3.5943 sweet sorghum stalk-based carbon material 411.422 7.3788 lead-coated sweet sorghum stalk-based carbon material 186.377 6.6952 (Fig. 11 and Table 7) Figure 11 (a) shows that the specific surface area of sweet sorghum stalk after pretreatment is 13.0337 m 2 /g, the peak pore size change rate of biomass sweet sorghum stalk is near 4.7 nm. The specific surface area of the sweet sorghum stalk-based carbon material is 411.422 m 2 /g, which indicates that the carbon material with a large specific surface area is obtained by high temperature treatment, with 7.5 nm pore diameter. After coating Pb, the specific surface area of the lead-coated sweet sorghum stalk-based carbon material is 186.377 m 2 /g, the lead particles may be adsorbed on the surface or pores of the sweet sorghum stalk-based carbon material, resulting in a decrease in the specific surface area of the carbon material[ 41 ], the pore diameter is around 7.0 nm. As can be seen from Table 7 , the average pore diameters of the three materials were 3.59, 7.37, and 6.69 nm, respectively. It shows that the average pore size has not been reduced too much during the coating process, indicating that the coating process has a weak effect on the pore size. In addition, the coexistence of micropores and mesopores in the hybrid combination of the specific surface area of sweet sorghum stalk-based carbon material and lead particles is beneficial to improve and improve the transport rate and conductivity of ions during battery operation[ 42 ]. (4) XRD analysis Figure 12 is XRD figures of the pretreated sweet sorghum stalk(a), sweet sorghum stalk-based carbon material(b), and lead-coated sweet sorghum stalk-based carbon material(c). (Fig. 12 ) It can be seen from Fig. 12 (a) that there is a obvious and sharp carbon diffraction peak at 2θ of 21.9°, indicating that the sweet sorghum rods after pretreatment are mainly cellulose with high carbon content and good crystallinity. There is a distinct bulge diffraction peaks at 2θ of 24° and 44°, which is a characteristic diffraction peaks of the carbon material in Fig. 12 (b), so it can be considered a carbon material was produced. XRD spectrum of lead-coated sweet sorghum stalk-based carbon material in Fig. 12 (c) is compared with a standard card, and characteristic diffraction peaks appearing at 2θ of 31.361°, 36.342°, 52.551°, and 62.258° respectively, which correspond to Pb (1,1, 1), (2,0,0), (2,2,0) and (3,1,1) crystal faces, it shows that the solvent-coated method can successfully prepare lead-coated carbon materials[ 43 , 44 ]. Performance characterization of lead carbon batteries (1) The first charge and discharge curve According to the procedure of " Preparation of positive and negative materials for lead carbon batteries", a negative electrode material (lead paste) containing a lead-coated carbon material was assembled into a simulated lead carbon battery. After the formation process, under the condition of constant current 3.5 C, the first charge and discharge curve test of lead-coated carbon material(a) and control sample material (b) were performed, and the cutoff voltage was 1.70 V. The results are shown in Fig. 13 . (Fig. 13) It can be clearly seen that initial discharge voltage of lead carbon batteries with lead-coated sweet sorghum stalk-based carbon material and the physical grinding compared material are 2.32 and 2.28 V, respectively, and their discharge platform are 1.98 ~ 1.86V and 1.97 ~ 1.91 V, respectively, these indicate the initial discharge voltage of the lead-coated carbon material formed by the solvent method is high, and the discharge platform is also high, this indicates that the stability of the material is high, and a stable output can be achieved at a high voltage, in addition, the first discharge specific capacity is 73.0 mAh/g after reaching the cutoff voltage (1.70 V), and the first discharge specific capacity of the the physical grinding compared material is 57.24 mAh/g. Comparing the discharge specific capacity of the two materials after reaching the cut-off voltage, the performance of the lead-coated sweet sorghum stalk-based carbon material prepared by the solvent method had been improved by 27.53%. (2) Cycle life analysis Finally, the lead paste containing lead-coated sweet sorghum stalk-based carbon material was assembled into a simulated lead carbon battery, and the Neware BTS high-precision battery test system (CT-48-5V 20A) was used after the battery was fully charged, the battery cycle life test of lead-coated sweet sorghum stalk-based carbon material(a) and physical grinding compared material(b) were performed, and the results are shown in Fig. 14 . (Fig. 14 ) The capacity of the negative electrode materials prepared by different methods was different after 150 cycles, the specific capacity retention ratio of the lead-coated sweet sorghum stalk-based carbon material was 71.8%, and the specific capacity retention ratio of the physical grinding compared material was only 57.5%. In summary, assembled batteries containing lead-coated sweet sorghum stalk-based carbon material has better charge and discharge efficiency and cycle performance. This is mainly due to the better interfacial compatibility between the sweet sorghum stalk-based carbon material and the negative active material lead in the lead-coated carbon material prepared by the solvent method, so that the utilization ratio of the active material is greatly improved, and thus the specific capacity is high and the cycle performance is good. Conclusion The lead-coated sweet sorghum stalk-based carbon material was successfully prepared by solvent method with sweet sorghum stalk as carbon source, it was applied to lead-carbon battery, the lead-carbon battery consisting of lead-coated sweet sorghum stalk-based carbon material was tested by a charge and discharge device, which showed that the first discharge specific capacity was 73.0 mAh/g, and the capacity retention after 150 cycles was 71.8%. The characteristic of the lead-coated sweet sorghum stalk-based carbon material is that the interface resistance between the carbon material and the metal lead was reduced, and the conductive network constructed in the anode material increases the conductivity of the negative material and improved the utilization ratio of the active material, thereby improving the capacity of lead carbon battery. Carbon materials prepared from sweet sorghum stalks partially replaced the active material of lead carbon battery, which not only improved the comprehensive utilization degree of sweet sorghum stalks, but also applies the modification of sweet sorghum stalk-based carbon material to batteries, which has potential significance. Declarations Author Contribution Credit author statementQiuqun Liang: investigation; validation; writing-original draft. Xiaoqi Lan: supervision; review.Zheng Liu: writing-review & editing; supervision.Junjie Ma: investigation validation; design. Guo-Cheng Han: conceptualization; writing-review & editing; supervision. Hao Wang: investigation validation; supervision; review. 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Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 03 Oct, 2024 Reviews received at journal 29 Sep, 2024 Reviewers agreed at journal 24 Sep, 2024 Reviewers agreed at journal 23 Sep, 2024 Reviews received at journal 04 Sep, 2024 Reviewers agreed at journal 14 Aug, 2024 Reviewers invited by journal 12 Aug, 2024 Editor assigned by journal 12 Aug, 2024 Submission checks completed at journal 12 Aug, 2024 First submitted to journal 08 Aug, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4881412","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":349403881,"identity":"3da99942-9967-4fac-a33a-19da0f86a123","order_by":0,"name":"Qiuqun Liang","email":"","orcid":"","institution":"Liuzhou Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Qiuqun","middleName":"","lastName":"Liang","suffix":""},{"id":349403882,"identity":"c70c0b05-6354-414b-bb34-a820a6d1ecf8","order_by":1,"name":"Xiaoqi Lan","email":"","orcid":"","institution":"Guilin University of Technology Key Laboratory of 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H\u003csub\u003e3\u003c/sub\u003eP\u003csub\u003e4\u003c/sub\u003e solution\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/572e2d62b03bb960eeb65a96.jpg"},{"id":64086858,"identity":"2259b5c9-4a62-46e7-8507-b142266ad55b","added_by":"auto","created_at":"2024-09-06 12:54:52","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":34545,"visible":true,"origin":"","legend":"\u003cp\u003eTG curves of sweet sorghum stalk with different pretreatments\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/2bba0b9ab40437e4fa4e0dba.jpg"},{"id":64086453,"identity":"c0dd49bc-a2d2-441a-a918-9ca813b1cb94","added_by":"auto","created_at":"2024-09-06 12:46:52","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":57327,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of sweet sorghum stalk with different pretreatment: (a) and (b): 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e, (c) and (d): 36 wt.% CH\u003csub\u003e3\u003c/sub\u003eCOOH and 68 wt.% HNO\u003csub\u003e3\u003c/sub\u003e solution, (e) and (f): 10 wt.% NH\u003csub\u003e3\u003c/sub\u003e∙H\u003csub\u003e2\u003c/sub\u003eO solution, (g) and (h): 5 wt.% NaOH solution\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/0c2f6553e7ab5450f63d3a5c.jpg"},{"id":64086857,"identity":"e88b57c8-4ae3-4044-805d-7888000908d6","added_by":"auto","created_at":"2024-09-06 12:54:52","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":43445,"visible":true,"origin":"","legend":"\u003cp\u003eRaman spectrum of sweet sorghum stalk-based carbon materials with different temperature\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/629a403627cd6663d25a1b0b.jpg"},{"id":64086444,"identity":"b6059b0e-7080-49f4-9b38-d58ed78c7319","added_by":"auto","created_at":"2024-09-06 12:46:52","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":44064,"visible":true,"origin":"","legend":"\u003cp\u003eRaman spectrum of sweet sorghum stalk-based carbon materials at different carbonization time\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/f68079189cc46d739ba86a85.jpg"},{"id":64086863,"identity":"7222b33f-cb77-45eb-a9a4-8ce64dd78121","added_by":"auto","created_at":"2024-09-06 12:54:52","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":176886,"visible":true,"origin":"","legend":"\u003cp\u003eNitrogen adsorption-desorption test diagram and pore diameter distribution diagram of sweet sorghum stalk-based carbon materials under different carbonization times (inset): (a)-(g) were 30~120 min (the time gradient is 15 min), respectively.\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/5e9b83b2147c64b4daa2ecd1.jpg"},{"id":64086448,"identity":"d410539a-cff9-413c-8d15-761c74f368cb","added_by":"auto","created_at":"2024-09-06 12:46:52","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":49395,"visible":true,"origin":"","legend":"\u003cp\u003eEIS curves of lead-carbon coating materials at different reduction times(The inset is equivalent circuit diagram of EIS and a drawing of partial EIS enlargement of lead-coated carbon material in the range of 0~2 Ω at different reduction times)\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/f0cc3c54f47c88f8043828c3.jpg"},{"id":64086443,"identity":"25e87a2c-bb6b-478a-8a7b-8f59b4dfa299","added_by":"auto","created_at":"2024-09-06 12:46:52","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":48686,"visible":true,"origin":"","legend":"\u003cp\u003eCV curves of lead-coated sweet sorghum stalk-based carbon materials at different reduction time\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/d73b07627e2cee759706ac37.jpg"},{"id":64087477,"identity":"33f7282e-3ef6-4bf7-aa90-ac90bc38e3f3","added_by":"auto","created_at":"2024-09-06 13:10:52","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":104439,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of three materials: (a) 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e pretreated sweet sorghum stalk; (b) the sweet sorghum stalk-based carbon material; (c) the lead-coated sweet sorghum stalk-based carbon material\u003c/p\u003e","description":"","filename":"9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/f12b989c602e4c6ecf56903f.jpg"},{"id":64087147,"identity":"fbc8f7d5-d38e-430e-9a76-03f0742e00c3","added_by":"auto","created_at":"2024-09-06 13:02:52","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":40608,"visible":true,"origin":"","legend":"\u003cp\u003eEDS spectrum of three materials(sweet sorghum stalk, sweet sorghum stalk-based carbon material, lead-coated sweet sorghum stalk-based carbon material)\u003c/p\u003e","description":"","filename":"10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/3690b65c490fff3e6c548439.jpg"},{"id":64086860,"identity":"0cfc3003-8161-4835-91a6-12e370ad9a7d","added_by":"auto","created_at":"2024-09-06 12:54:52","extension":"jpg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":74957,"visible":true,"origin":"","legend":"\u003cp\u003eNitrogen adsorption-desorption test diagram (insert is pore diameter distribution diagram of three materials)\u003c/p\u003e","description":"","filename":"11.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/df0cb23cb141a20bb1670b97.jpg"},{"id":64087144,"identity":"bdfdde4c-5dc4-44e1-a36a-aca7e5a46681","added_by":"auto","created_at":"2024-09-06 13:02:52","extension":"jpg","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":50732,"visible":true,"origin":"","legend":"\u003cp\u003eXRD spectrum of three materials(sweet sorghum stalk, sweet sorghum stalk-based carbon material, lead-coated sweet sorghum stalk-based carbon material)\u003c/p\u003e","description":"","filename":"12.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/d4820d04a25c1ca21bfc78b0.jpg"},{"id":64087764,"identity":"e66503e2-6dfd-49bc-a5f2-4221496d97a3","added_by":"auto","created_at":"2024-09-06 13:18:52","extension":"jpg","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":37311,"visible":true,"origin":"","legend":"\u003cp\u003eFirst discharge curves of lead-coated sweet sorghum stalk-based carbon material(a) and the physical grinding compared material(b)\u003c/p\u003e","description":"","filename":"13.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/9d72ac87c21d6c6205dffb67.jpg"},{"id":64086455,"identity":"ccb22439-4046-4578-8538-ca312e181803","added_by":"auto","created_at":"2024-09-06 12:46:52","extension":"jpg","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":41096,"visible":true,"origin":"","legend":"\u003cp\u003eCycle life curves of lead-coated sweet sorghum stalk-based carbon material(a) and the physical grinding compared material(b)\u003c/p\u003e","description":"","filename":"14.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/013f1358ad9eab0c8b2b031b.jpg"},{"id":64776171,"identity":"f349e72b-1986-403a-af93-edd591f2b857","added_by":"auto","created_at":"2024-09-18 16:28:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1815109,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4881412/v1/eff0d1cd-677e-4a19-9329-463e4b3bc311.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Preparation of lead-coated sweet sorghum stalk-based carbon material and its electrochemical performance","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLead-acid batteries play an important role in the global rechargeable battery market due to their low cost, mature manufacturing process and recyclability, and are widely used in automotive and industrial fields[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], especially in the field of low-speed electric vehicle applications have great advantages[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. However, when the lead-acid battery is in a partially charged state with high rate charge and discharge mode, the negative electrode PbSO\u003csub\u003e4\u003c/sub\u003e cannot be reduced to sponge lead in time. As the discharge state continues, large particles of PbSO\u003csub\u003e4\u003c/sub\u003e will gradually accumulate on the surface of the negative electrode, forming a layer of dense PbSO\u003csub\u003e4\u003c/sub\u003e crystals, resulting in a decrease in the area of the negative electrode active substances. It affects the charging and discharging efficiency and the cycle life of lead-acid batteries [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], thus limiting the application of lead-acid batteries in new energy vehicles [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In order to solve this problem, a carbon material is added to the negative electrode material of the lead-acid battery, and the lead-carbon battery is formed[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs a lead carbon battery developed on the basis of lead-acid batteries, it is a new type of battery that combines the high energy density of lead-acid batteries with the high power density of supercapacitors, it is widely used in the field of device energy storage and power battery, and the lead carbon battery is similar to the traditional lead-acid battery production process, and the industrialization is relatively easy. The addition of carbon material to the negative electrode of the lead carbon battery can solve the irreversible sulfation of the battery under high-rate charge and discharge conditions to a certain extent, thereby prolonging the service life of the lead carbon battery[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The main reason is the added carbon material, the conductive network that can be built in the negative electrode material, the increase of the electric double layer capacitance performance, and the increase of reactive sites[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The addition of carbon materials has also brought certain problems, for example, there is an obvious phase interface between carbon material and negative active material, this phenomenon will cause the battery to run interrupted under high-rate charge and discharge conditions for a long time[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In addition, due to the addition of the carbon material, the hydrogen evolution overpotential of the negative electrode is reduced, a hydrogen evolution phenomenon is generated during the charging process, and after a plurality of cycles, the electrolyte loss can be caused, and the sulfuric acid concentration of the electrolyte increases, further causing the sulphation of the negative electrode to be intensified[21,22.23]. Therefore, it is of great significance to study and solve the above problems encountered in lead-carbon batteries. Naresh and co-workers[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] used industrial asphalt as a carbon source to combine with SnO\u003csub\u003e2\u003c/sub\u003e under high temperature conditions, and finally prepared carbon-coated SnO\u003csub\u003e2\u003c/sub\u003e materials. The results show that the carbon layer can improve the conductivity and charge storage performance of the anode active material, thereby improving the capacity and cycle performance of the battery, at the same time, C/SnO\u003csub\u003e2\u003c/sub\u003e occupies the pores of the negative active material, suppresses the growth of PbSO\u003csub\u003e4\u003c/sub\u003e and reduces the precipitation of hydrogen. When the composite is added to the lead-acid battery, the charging rate of the composite under the condition of high rate partial charge is 300% higher than that of the traditional lead-acid battery. Zhang and co-workers[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] used rice husk-derived ultra-large micron-sized porous carbon and commercial activated carbon as composite electrode materials for lead-carbon batteries, tested under high-rate partially charged state (HRPSoC) conditions, the composite electrode with rice husk derived carbon has high coulombic efficiency (close to 100%) and long cycle life during operation, this is because commercial activated carbon has smaller micropore structure and higher specific surface area than rice husk derived carbon, when a large number of commercial activated carbon is added, lead-carbon batteries have obvious hydrogen evolution, which leads to capacity attenuation and coulomb efficiency reduction. Lead-carbon composites with rice husk derived carbon provide a larger carbon surface for electrodeposition of lead because of the rough surface of rice husk derived carbon, a stable structure is formed in the process of charge and discharge, so it has stable capacity and coulomb efficiency. Zhang and co-workers[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] prepared a graphene-like two-dimensional carbon/PbSO\u003csub\u003e4\u003c/sub\u003e composite by simple chemical vapor deposition and ion exchange, the results show that the composite can effectively improve the electrical conductivity and ionic conductivity of the material, and can effectively inhibit the irreversible sulfation of the negative electrode during the operation of HRPSoC, in addition, PbSO\u003csub\u003e4\u003c/sub\u003e deposited on the layered carbon can uniformly mix the carbon additive with the active material, and can inhibit the occurrence of hydrogen evolution to a certain extent, thereby improving the high rate charge and discharge performance of the lead-acid battery. Energy grass is a general term for annual tall herbaceous plants, the ideal energy grass species mainly include sweet sorghum, switchgrass, and pennisetum[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Sweet sorghum is the most widely used energy grass in the energy field, India, Australia and other countries have carried out research on the production of ethanol fuel from sweet sorghum[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], compared with other cash crops, sweet sorghum has great advantages in terms of yield and economic benefits[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. In addition, sweet sorghum is widely used in wine making[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], papermaking[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], and sugar making[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Khalil and co-workers[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] used sweet sorghum stalk as carbon source and impregnated with activator ZnCl\u003csub\u003e2\u003c/sub\u003e to prepare carbon materials with different surface areas at different pyrolysis temperatures to adsorb harmful cationic dyes and achieved good adsorption. Xu and co-workers[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]used sweet sorghum stalk as carbon source, flake carbon structure was prepared by carbonation and applied to high energy lithium ion capacitors, after 5000 cycles at 10 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e current, the capacity retention rate is 66%, which has good power performance.\u003c/p\u003e \u003cp\u003eIn order to improve the comprehensive utilization of energy grass, waste sweet sorghum stalk was used as carbon source to prepare lead-coated sweet sorghum stalk-based carbon materials by solvent method in this paper. The bonding structure, thermal stability and morphology of the sweet sorghum stalks after pretreatment were analyzed by infrared light spectrum(IR), thermogravimetric curve(TG) and scanning electron microscope(SEM), the graphitization degree of the sweet sorghum stalk-based carbon materials were analyzed by Raman spectroscopy (Raman), the electrochemical properties of lead-coated sweet sorghum stalk-based carbon materials were analyzed by cyclic voltammetric (CV) and electrochemical AC impedance method(EIS), then, the energy dispersive spectroscopy (EDS), X-ray powder diffraction spectrum(XRD), and BET curve were used to compare and analyze the morphology, element content, phase structure, specific surface area and pore size distribution of the pretreated sweet sorghum stalk, the prepared sweet sorghum stalk-based carbon material, and the prepared lead-coated the sweet sorghum stalk-based carbon material under the optimal conditions. The self-made lead-coated carbon material was mixed with a battery auxiliary to prepare a negative electrode material, and finally assembled into a simulated lead carbon battery, the first discharge performance and cycle performance of the battery were tested and analyzed.\u003c/p\u003e"},{"header":"Experimental part","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMaterials and reagents\u003c/h2\u003e \u003cp\u003eThe sweet sorghum stalk was provided from Hengshui Farm in Hebei Province. The chemical reagents used were purchased from Aladdin Reagent (Shanghai Co., Ltd.), Xilong chemical co., Ltd., Chaowei Battery Company and Tianjin Guangfu Fine Chemical Research Institute. The lead calcium alloy anode plates were obtained from Baoding Meilun Nonferrous Metal Co., Ltd., lead dioxide cathode plates were acquired from Baoji Changli Special Metal Co., Ltd., AGM separators were purchased from Yingkou Zhongjie Shida Separator Co., Ltd. The laboratory water was homemade distilled water.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003ePretreatment of sweet sorghum stalk\u003c/h2\u003e \u003cp\u003eThe sweet sorghum stalk was washed with distilled water, then was placed in a blast drying box, and dried at 60\u0026deg;C for 12 h, and then was cut into small pieces of 1 cm with scissors. The sweet sorghum stalk was soaked in the prepared 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e solution and treated at 50\u0026deg;C for 24 h. The treated sweet sorghum stalk was separated, rinsed with distilled water until the material was neutral, and dried in an oven at 90\u0026deg;C for 24 h.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of lead-coated sweet sorghum stalk carbon material\u003c/h2\u003e \u003cp\u003eThe dried sweet sorghum stalk had been placed in a closed grinding mill for grinding and grounded into a 300\u0026ndash;400 mesh powder. 2.0 g sweet sorghum stalk powder had been weighed and transferred into a quartz boat. The quartz boat had been placed in a vacuum tube furnace and heated at 550\u0026deg;C for 105 min under an argon atmosphere, the flow rate of the argon gas had been controlled to 100 mL/min, the heating rate was 5\u0026deg;C/min, and the temperature was naturally cooled to room temperature, that was, a sweet sorghum stalk-based carbon material was obtained.\u003c/p\u003e \u003cp\u003e3.31 g of Pb(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e had been dissolved in 50 mL of distilled water, 1.89 g of NaBH\u003csub\u003e4\u003c/sub\u003e had been dissolved in 50 mL of distilled water, and 0.01 g of sweet sorghum stalk-based carbon material had been dissolved in 50 mL of absolute ethanol. The Pb(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e solution had been placed in a flask, and added 25 mL of ethanol solution of sweet sorghum stalk-based carbon material while stirring for 1 h. The reducing agent NaBH\u003csub\u003e4\u003c/sub\u003e solution had been added dropwise in an ice water bath and stirred for 45 min until a black precipitate (Pb) was formed. The black precipitate had been filtered, and the remaining 25 mL of a sweet sorghum-based carbon material ethanol solution had been added to the filtrate, stirred for another 45 min, and then black precipitate was separated again. The black precipitate had been washed several times with ethanol and water and dried in a vacuum oven at 50\u0026deg;C for 8 h to obtain a lead-coated carbon material.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of positive and negative materials for lead carbon batteries\u003c/h2\u003e \u003cp\u003eThe 0.5 g lead-coated sweet sorghum stalk-based carbon material, negative active material(lead oxide 3 g), conductive agent(acetylene black 0.15 g), expander (humic acid 0.09 g, barium sulfate 1.8 g)and antioxidant (barium stearate 0.9 g) had been uniform mixed, grinded in an agate mortar for 20 min, after several powders are thoroughly mixed, transfer the material to a 250 mL beaker, then added 6 mL of 60% polytetrafluoroethylene (PTFE) emulsion, a certain amount of distilled water, and 6 mL of 1.38 g/cm\u003csup\u003e3\u003c/sup\u003e sulfuric acid solution, mechanically stirred until a paste substance was formed, that was, a lead carbon battery negative material (lead paste) was obtained.\u003c/p\u003e \u003cp\u003eThe positive active material(lead dioxide 10 g, lead oxide 3 g), conductive agent(acetylene black 0.15 g), antioxidant (barium stearate 0.9 g) and barium sulfate (1.8 g) had been uniform mixed, grinded in an agate mortar for 20 min, after several powders had been thoroughly mixed, transfer the material to a 250 mL beaker, then added 6 mL of 60% polytetrafluoroethylene (PTFE) emulsion, a certain amount of distilled water, and 6 mL of 1.38 g/cm\u003csup\u003e3\u003c/sup\u003e sulfuric acid solution, mechanically stirred until a paste substance was formed, that was, a lead carbon battery positive material was obtained.\u003c/p\u003e \u003cp\u003eThe lead carbon battery negative and positive materials had been respectively applied to the negative and positive slab lattice, uniformly coated and compacted, and then the electrode plates had been placed in an oven at 60\u0026deg;C for 12 h to obtain the positive and negative electrodes of the lead carbon battery.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eMaterial characterization\u003c/h2\u003e \u003cp\u003eThe TG curves and IR spectra of the pretreated sweet sorghum stalk were determined by the thermogravimetric analyzer of SDT-Q600 of American TA Company and the Fourier transform infrared spectrometer of Thermo Fisher iS10 type by American Thermo Fisher Company, the SU5000-type field emission scanning electron microscope of Hitachi(Japan) was used to test the surface characteristics of the pretreated sweet sorghum stalk and the morphology of the lead-coated sweet sorghum stalk-based carbon material, the test conditions were voltage 3kV, emission current 10100 nA, working distance 6000 \u0026micro;m. The elemental content of the lead-coated sweet sorghum stalk-based carbon material was determined by the XFlash6l10 Bruker type energy spectrum system of the company, test conditions were as follows: working distance was 5\u0026ndash;40 mm, spatial resolution was 0.5 \u0026micro;m, angular resolution was 0.50. The Raman spectra of carbon materials prepared at different activation temperatures were determined by Inrivia laser Raman spectrometer from Renishaw, UK, the laser wavelength was 514 nm, the graphitization degree of carbon materials was measured by analyzing the intensity ratios of D and G peaks of carbon materials, the phase composition and phase structure of lead-coated sweet sorghum stalk-based carbon material were characterized by X'Pert3-Power X-ray powder diffraction apparatus of Panaco, Netherlands. The test conditions were as follows: test voltage was 40kv, current was 40 mA, Cu(Kα)target, λ\u0026thinsp;=\u0026thinsp;1.54426, scan rate was 16⁰ min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, scan range was 10\u0026thinsp;~\u0026thinsp;90⁰, the pore volume, pore size and specific surface area of the lead-coated sweet sorghum stalk-based carbon material were analyzed by V-Sorb 2800TP specific surface adsorption instrument of Beijing Jine Spectrum Technology Co., Ltd.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eElectrochemical performance test\u003c/h2\u003e \u003cp\u003eThe CHI760 electrochemical workstation(Shanghai Chenhua Instrument Co., Ltd.) was used, and the negative electrode of the self-made lead carbon battery was used as the working electrode, the reference electrode of the calomel electrode was used as the reference electrode, the platinum wire electrode was used as the auxiliary electrode, and the sulfuric acid solution of 1.05 g/mL was used as the electrolyte, the three-electrode system was subjected to CV and EIS. CV conditions were as follows: scan potential interval was \u0026minus;\u0026thinsp;1.2\u0026thinsp;~\u0026thinsp;0.1 V, scan rate was 0.01 mV/s; EIS test parameter was set to 0.5\u0026thinsp;~\u0026thinsp;10000 Hz, initial potential was open circuit potential, and amplitude was 5 mV. The specific capacitance of the carbon material electrode can be calculated according to the formula(1):\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:\\text{C}=\\frac{1}{mv({V}_{c}-{V}_{a})}{\\int\\:}_{{V}_{a}}^{{V}_{c}}{I}_{V}{d}_{V}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere C is the specific capacitance (F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), m is the mass (g) of the active material on the electrode, and v is the scanning rate (V s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), (V\u003csub\u003ec\u003c/sub\u003e-V\u003csub\u003ea\u003c/sub\u003e) is the potential range (V) during discharge, and I\u003csub\u003ev\u003c/sub\u003e is the response current density (A cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e)[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The electrochemical impedance spectroscopy was analyzed by Z-View software, in which Rs is the material resistance of the negative electrode, R1 is the solution resistance, C1 is the solution capacitance, and CPE is the electrode/solution interface capacitance.\u003c/p\u003e \u003cp\u003eThe lead carbon battery was assembled according to the positive and negative plates prepared by 2.4 and the AGM diaphragm, the electrolyte was 1.14 g/mL sulfuric acid solution, and using CT-3008-5V-20A Neware battery test system, the first cycle charge and discharge performance test of the assembled simulated lead carbon battery was carried out by constant current circulating charge and discharge method, the control current was 750 mA and the cut-off voltage was 1.70 V. At the same time, the cycle life of the simulated battery was measured, and the electrochemical cycle stability of the carbon material was analyzed.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003ePretreatment optimization of sweet sorghum stalk\u003c/h2\u003e \u003cp\u003eSweet sorghum stalk was pretreated with 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e solution, mixed acid solution (36 wt.% CH\u003csub\u003e3\u003c/sub\u003eCOOH and 68 wt.% HNO\u003csub\u003e3\u003c/sub\u003e solution), 10 wt.% NH\u003csub\u003e3\u003c/sub\u003e∙H\u003csub\u003e2\u003c/sub\u003eO solution and 5 wt.% NaOH solution. The pretreated sweet sorghum stalk was measured by IR, TG and SEM as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e to Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e, respectively.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eClassically, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e is an IR spectrum of four different pre-treated sweet sorghum stalk. The absorption peaks around 3340 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 2920 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1735 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1590 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1430 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and 1050 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be attributed to C-H stretching vibration, C-H stretching vibration of methyl and methylene, C\u0026thinsp;=\u0026thinsp;O stretching vibration of polyxylose, C\u0026thinsp;=\u0026thinsp;O stretching vibration of lignin, C\u0026thinsp;=\u0026thinsp;O stretching vibration of hemicellulose, and C\u0026thinsp;=\u0026thinsp;O stretching vibration of cellulose and hemicellulose, respectively. Among the above four pretreatment conditions, the treatment of 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e is more thorough in the decomposition of polyxylose and hemicellulose. In the mixed acid, due to the addition of HNO\u003csub\u003e3\u003c/sub\u003e, the decomposition of poly-xylose and hemicellulose by CH\u003csub\u003e3\u003c/sub\u003eCOOH has a certain hindrance effect. Therefore, a C\u0026thinsp;=\u0026thinsp;O stretching vibration peak in polyxylose and hemicellulose appears. When the sweet sorghum stalk treated with 10 wt.% NH\u003csub\u003e3\u003c/sub\u003e∙H\u003csub\u003e2\u003c/sub\u003eO and 5 wt.% NaOH, the characteristic absorption peaks of lignin and cellulose both appeared, which indicated that the degree of cellulose decomposition of lignin in sweet sorghum stalk was small. However, the sweet sorghum stalk treated with 5 wt.% NaOH, the characteristic absorption peak of hemicellulose appeared.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e is TG curves of sweet sorghum stalk with different pretreatment.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eIt can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e that a certain amount of weight loss occurs in the vicinity of 70\u0026deg;C\u0026thinsp;~\u0026thinsp;80\u0026deg;C. This phenomenon occurs because the sweet sorghum stalk contains a certain amount of adsorbed water, and with the increase of temperature, the water in the sweet sorghum stalk is volatilized, that is, the weight loss in the interval of 70\u0026deg;C\u0026thinsp;~\u0026thinsp;80\u0026deg;C is the weight loss caused by the thermal evaporation of water. After 80\u0026deg;C, the TG curves entered the platform, indicating that the sample was in a thermally stable state. 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e treated sample, the TG curves declined at 150℃, and the TG curves appeared on the platform at 800℃, and the residual rate of the sample was 10%, the weight loss temperature of the other pretreated samples was about 200℃, and the platform temperature of TG curve was lower than that of 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e treatment samples, and the residual rate of the samples were also low. Thermogravimetric analysis showed that the carbon material with high yield could be obtained by treating the sample with 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e. This may be due to the fact that phosphate can effectively dissolve the pectin in sweet sorghum stalk, while lignin and cellulose dissolve less in sweet sorghum stalk[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe surface morphology of the treated sweet sorghum stalk was characterized, the results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e(a) and (b) showed that the sweet sorghum stalk tubular bundle after phosphoric acid treatment is more obvious, and the impurities of small particles on the surface are less. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e(c) and (d) showed that the tubular bundle of the sweet sorghum stalk treated by the mixed acid treatment has a large degree of damage and a rough surface, which may be caused by a certain depolymerization of cellulose. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e(e) and (f) showed that the tubular bundle of the sweet sorghum stalk treated with NH\u003csub\u003e3\u003c/sub\u003e∙H\u003csub\u003e2\u003c/sub\u003eO has a large degree of damage and a large distribution of surface particles, which indicates that the surface-adhered impurities have not been completely removed. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e(g) and (h) illustrated that the surface of the sweet sorghum stalk treated with NaOH is rougher. Therefore, the optimal pretreatment method for determining the sweet sorghum stalk is to use 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e treatment by analysis of the above three characterization methods.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eOptimization of preparation conditions for lead-coated sweet sorghum stalk-based carbon materials\u003c/h2\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e(1)Temperature optimization\u003c/h2\u003e \u003cp\u003eTemperature is a very important factor for material preparation. The obtained sweet sorghum stalk-based carbon material samples were subjected to Raman test according to the method of \u003cb\u003e\"Preparation of positive and negative materials for lead carbon batteries\u003c/b\u003e\", as shown in the Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e, calculated the R value list it in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eR value of sweet sorghum stalk-based carbon materials at different temperatures.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePreparation temperature of sweet sorghum stalk-based carbon material/\u0026deg;C\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCrystallite size (La)/nm\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8433\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.16\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e450\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8269\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.7694\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.65\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e550\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.7427\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.86\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8539\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e650\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8572\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8623\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e750\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8679\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8992\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.84\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e850\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.9188\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.73\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e900\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.9394\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.63\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eIt can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e that with different preparation temperature, the peak D peak of prepared sweet sorghum stalk-based carbon material appears in 1360 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which belongs to A\u003csub\u003e1g\u003c/sub\u003e mode, which is the Raman activity of crystallization boundary region in graphite of sweet sorghum stalk-based carbon materials, contribute to the crystallization size effect. The G peak appears near 1580 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and belongs to the E\u003csub\u003e2g\u003c/sub\u003e mode, it appears in all carbon fiber spectra, the presence of the 1580 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e peak is the basis of the graphite structure of the sweet sorghum stalk-based carbon materials[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. The R ratios of I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e are listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. It can be seen that the carbon material with the highest graphitization degree can be obtained by heating at 550℃, so 550℃ is the most suitable preparation temperature.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e(2)Carbonization time optimization\u003c/h2\u003e \u003cp\u003eThe carbonization experiment was carried out at 550\u0026deg;C in accordance with the method of \u003cb\u003e\"Preparation of positive and negative materials for lead carbon batteries\u003c/b\u003e\", and the obtained samples of the sweet sorghum stalk-based carbon material was subjected to Raman spectra and BET test. The results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e to Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e8\u003c/span\u003e, and the R value was calculated as shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eR value of sweet sorghum stalk-based carbon materials at different carbonization times.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarbonization time / min\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCrystallite size (La)/nm\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8783\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.9527\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.9296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.6794\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8755\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.9686\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.9505\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.5765\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.9159\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.7494\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e105\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8643\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.0329\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.9015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.8253\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eIt can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e that the Raman spectrum R values of the sweet sorghum stalk-based carbon material samples prepared at different carbonization time are quite different, and the R value was calculated, obtaining that when the preparation time was 105 min, the graphitization degree of the sweet sorghum stalk-based carbon material was the highest.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e6\u003c/span\u003e is a nitrogen adsorption-desorption curve diagram and a pore size distribution diagram (insert) of the sweet sorghum stalk-based carbon material at different carbonization times, and the data obtained in the figure are summarized and listed in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSpecific surface area and pore size of sweet sorghum stalk-based carbon materials under different carbonization times.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarbonization time / min\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSpecific surface area / (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePore width / nm\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e233.131\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e27.395\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e258.428\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.086\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e280.083\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.956\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e307.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.274\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e313.093\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.086\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e105\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e411.422\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.086\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e346.918\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.086\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e6\u003c/span\u003e andTable 3)\u003c/h2\u003e \u003cp\u003eIt can be seen from Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e that as the carbonization time increases, the specific surface area of the sweet sorghum stalk-based carbon material increase first and then decrease. When the carbonization time is 105 min, the specific surface area is the highest, which is 411.422 m\u003csup\u003e2\u003c/sup\u003e/g. It can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e6\u003c/span\u003e that the sweet sorghum stalk-based carbon materials have a certain degree of hysteresis loop with different carbonization time, indicating that the carbon material contain a partial mesoporous structure\u003csup\u003e37\u003c/sup\u003e, at the same time, the average pore diameter of the sweet sorghum stalk-based carbon materials were about 2 nm except for 27.393 nm with the carbonization time of 30 min.\u003c/p\u003e \u003cp\u003eThe optimum carbonization time of the sweet sorghum stalk-based carbon material was determined by Raman spectra and nitrogen adsorption-desorption curve diagram to be 105 min.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e(3)Reduction time optimization\u003c/h2\u003e \u003cp\u003eAccording to the step in \u003cb\u003e\"Preparation of positive and negative materials for lead carbon batteries\u003c/b\u003e\", the other conditions were kept same, and studied the time of sodium borohydride to reduce the lead nitrate ethanol solution of carbonaceous materials. The EIS curves and CV curves of the lead-coated sweet sorghum stalk-based carbon materials at different reduction times were tested. The results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e8\u003c/span\u003e, and the data obtained in the figures are obtained in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e to \u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The equivalent circuit is shown in the inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEIS spectrum datas of lead-coated sweet sorghum stalk-based carbon materials at different reduction times after fitting.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eImmersion time / min\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRs\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eC1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eR2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCPE-T\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eCPE-P\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.49433\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.021665\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.010921\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e15.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.53296\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.042484\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.056\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.28147\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.00060078\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e122.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.018089\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.59118\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.34654\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.15766\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.013518\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e82.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.06145\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.50419\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8946\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.305\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.00018223\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1042\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.01777\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.46238\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.40793\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.78361\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.016056\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e19.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.097772\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.44064\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCV datas of lead-coated sweet sorghum stalk-based carbon materials at different reduction times.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eImmersion time / min\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eArea enclosed by graphics / cm\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSpecific capacitance / F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.2837\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.8806\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.3125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8.6806\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.3767\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10.4639\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.2438\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.7722\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.3073\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8.5361\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eElement contents of three materials(sweet sorghum stalk, sweet sorghum stalk-based carbon material, lead-coated sweet sorghum stalk-based carbon material).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eMaterialsꞌ name\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e \u003cp\u003eProportion of each element\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC / %\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eO / %\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePb / %\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNa / %\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003esweet sorghum stalk\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e53.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e45.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003esweet sorghum stalk-based carbon material\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e74.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e21.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003elead-coated sweet sorghum stalk-based carbon material\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e71.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eIt can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e that the EIS spectrum has three main parts, the first part is the semicircle in the high frequency region, which is the ohmic impedance of the solution, the second part is the straight line in the medium frequency region, which mainly represents the diffusion resistance of electrolyte ions in the electrode gap, and the third part is the capacitance reactance in the low frequency region, which mainly represents the charge transfer impedance[\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. It can be seen from Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e that comparing the lead-coated sweet sorghum stalk-based carbon materials with different reduction time, it is found that the Rs of the lead-coated sweet sorghum stalk-based carbon materials prepared with a reduction time of 45 min is the smallest.\u003c/p\u003e \u003cp\u003eThe CV curves of lead-coated carbon materials at different reduction time were tested, the results were shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e8\u003c/span\u003e, and the area data were listed in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e.\u003c/p\u003e \u003cdiv id=\"Sec22\" class=\"Section3\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e8\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eIt can be concluded from Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e8\u003c/span\u003e that there is a pair of redox peaks on each curve, which indicates that the reaction has obvious capacitance characteristics, which is related to the redox reaction of Pb\u003csup\u003e2+\u003c/sup\u003e/Pb pairs in solution. In addition, depending on the immersion time, the positions of the redox peaks on each CV curves are different, and the peak current intensities are also different. It can be seen from Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e that the lead-coated sweet sorghum stalk-based carbon materials prepared at a reduction time of 45 min has the largest specific capacitance. This is because the reduction time is too long, and the addition of Pb(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e can be completely reduced to lead, and the carbon material is added in an amount, and the generated lead is greatly excessive, except for the carbon material, the remaining lead will agglomerate on the surface of the carbon material, hindering the formation of the lead-carbon conductive network channel and reducing the effect of the carbon material, so the peak current of the electric double layer is reduced and the specific capacitance is reduced. Coating lead particles on the surface of carbon materials can inhibit the formation of large size PbSO\u003csub\u003e4\u003c/sub\u003e, improve the conductivity, and inhibit the precipitation of hydrogen to a certain extent, thus improving the Faraday redox reaction and capacitance performance of the battery.\u003c/p\u003e \u003cp\u003eThe lead-coated sweet sorghum stalk-based carbon material with reaction time of 45 min has smaller migration resistance and larger specific capacitance. The migration resistance has an important influence on the electron-ion exchange process in the electrochemical reaction of negative electrode materials, the increase of specific capacitance can reduce the damage caused by high current charge and discharge to the electrode plate of lead carbon battery, in addition, it can provide partial electric double layer capacitors, which can increase the capacitance performance of lead carbon batteries.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003eCharacterization of materials\u003c/h2\u003e \u003cdiv id=\"Sec24\" class=\"Section3\"\u003e \u003ch2\u003e(1) SEM analysis\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e shows SEM of 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e pretreated sweet sorghum stalk (a), the sweet sorghum stalk-based carbon material (b), and the lead-coated sweet sorghum stalk-based carbon material (c).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eAfter 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e pretreatment, the sweet sorghum stalk still maintains a good tubular bundle structure Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e(a), indicating that lignin and cellulose are not destroyed, it provides the basis for the preparation of sweet sorghum stalk-based carbon material and lead-coated sweet sorghum stalk-based carbon material. It can be seen that the sweet sorghum stalk-based carbon material preserves the complete channel structure and improves the surface wettability of carbon materials and provides a better carbon substrate for lead coating in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e(b). Interesting, it can be clearly seen that the core-shell coating structure with carbon as the core and lead as the shell in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e(c), and the formed cladding structure has the characteristics of loose texture and porous, which has great correlation for the formation of electrochemical channels.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec26\" class=\"Section3\"\u003e \u003ch2\u003e(2) EDS Analysis\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e is an EDS spectrum of the pretreated sweet sorghum stalk (a), sweet sorghum stalk-based carbon material (b), and lead-coated sweet sorghum stalk-based carbon material (c), and the data of each element are listed in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec27\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eIt can be seen that the characteristic peaks of C and O appear in the scanning interval in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e(a), the carbon proportion of the sweet sorghum stalk is 53.85%, the oxygen proportion is 45.75%. From Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e(b), the peak intensity of the carbon element is significantly enhanced, the carbon proportion reach to 74.34%, and the oxygen proportion is 21.87%. After doping Pb, not only the characteristic peaks of C, Pb, and O elements, but also Na element appears, which may be due to the NaBH\u003csub\u003e4\u003c/sub\u003e reaction residue during the preparation process, the carbon content of the lead-coated sweet sorghum stalk-based carbon material is 9.26%, the oxygen content is 17.64%, and the lead content is as high as 71.42%. This indicates that lead is basically coated on the surface of the carbon material[\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e], it can continue to provide a pseudocapacitance effect for charging and discharging, and weaken the damage to the negative electrode during charging and discharging.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec28\" class=\"Section2\"\u003e \u003ch2\u003e(3) BET analysis\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e is nitrogen adsorption-desorption test diagram and pore diameter distribution diagram of three materials (insert) of the pre-treated sweet sorghum stalk(a), sweet sorghum stalk-based carbon material(b), and lead-coated sweet sorghum stalk-based carbon material(c), and the specific surface area and average pore diameter of the three materials are listed in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSpecific surface area and pore size of carbon material of three materials(sweet sorghum stalk, sweet sorghum stalk-based carbon material, lead-coated sweet sorghum stalk-based carbon material).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMaterialsꞌ name\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSpecific surface area / (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePore width / nm\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003esweet sorghum stalk\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e13.0337\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.5943\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003esweet sorghum stalk-based carbon material\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e411.422\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.3788\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003elead-coated sweet sorghum stalk-based carbon material\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e186.377\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.6952\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003e(Fig. 11 and Table 7)\u003c/h3\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e(a) shows that the specific surface area of sweet sorghum stalk after pretreatment is 13.0337 m\u003csup\u003e2\u003c/sup\u003e/g, the peak pore size change rate of biomass sweet sorghum stalk is near 4.7 nm. The specific surface area of the sweet sorghum stalk-based carbon material is 411.422 m\u003csup\u003e2\u003c/sup\u003e/g, which indicates that the carbon material with a large specific surface area is obtained by high temperature treatment, with 7.5 nm pore diameter. After coating Pb, the specific surface area of the lead-coated sweet sorghum stalk-based carbon material is 186.377 m\u003csup\u003e2\u003c/sup\u003e/g, the lead particles may be adsorbed on the surface or pores of the sweet sorghum stalk-based carbon material, resulting in a decrease in the specific surface area of the carbon material[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e], the pore diameter is around 7.0 nm. As can be seen from Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, the average pore diameters of the three materials were 3.59, 7.37, and 6.69 nm, respectively. It shows that the average pore size has not been reduced too much during the coating process, indicating that the coating process has a weak effect on the pore size. In addition, the coexistence of micropores and mesopores in the hybrid combination of the specific surface area of sweet sorghum stalk-based carbon material and lead particles is beneficial to improve and improve the transport rate and conductivity of ions during battery operation[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec30\" class=\"Section2\"\u003e \u003ch2\u003e(4) XRD analysis\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e is XRD figures of the pretreated sweet sorghum stalk(a), sweet sorghum stalk-based carbon material(b), and lead-coated sweet sorghum stalk-based carbon material(c).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec31\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eIt can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e(a) that there is a obvious and sharp carbon diffraction peak at 2θ of 21.9\u0026deg;, indicating that the sweet sorghum rods after pretreatment are mainly cellulose with high carbon content and good crystallinity. There is a distinct bulge diffraction peaks at 2θ of 24\u0026deg; and 44\u0026deg;, which is a characteristic diffraction peaks of the carbon material in Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e(b), so it can be considered a carbon material was produced. XRD spectrum of lead-coated sweet sorghum stalk-based carbon material in Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e(c) is compared with a standard card, and characteristic diffraction peaks appearing at 2θ of 31.361\u0026deg;, 36.342\u0026deg;, 52.551\u0026deg;, and 62.258\u0026deg; respectively, which correspond to Pb (1,1, 1), (2,0,0), (2,2,0) and (3,1,1) crystal faces, it shows that the solvent-coated method can successfully prepare lead-coated carbon materials[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec32\" class=\"Section3\"\u003e \u003ch2\u003ePerformance characterization of lead carbon batteries\u003c/h2\u003e \u003c/div\u003e \u003cdiv id=\"Sec33\" class=\"Section3\"\u003e \u003ch2\u003e(1) The first charge and discharge curve\u003c/h2\u003e \u003cp\u003eAccording to the procedure of \u003cb\u003e\"\u003c/b\u003ePreparation of positive and negative materials for lead carbon batteries\", a negative electrode material (lead paste) containing a lead-coated carbon material was assembled into a simulated lead carbon battery. After the formation process, under the condition of constant current 3.5 C, the first charge and discharge curve test of lead-coated carbon material(a) and control sample material (b) were performed, and the cutoff voltage was 1.70 V. The results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e\n\u003ch3\u003e(Fig. 13)\u003c/h3\u003e\n\u003cp\u003eIt can be clearly seen that initial discharge voltage of lead carbon batteries with lead-coated sweet sorghum stalk-based carbon material and the physical grinding compared material are 2.32 and 2.28 V, respectively, and their discharge platform are 1.98\u0026thinsp;~\u0026thinsp;1.86V and 1.97\u0026thinsp;~\u0026thinsp;1.91 V, respectively, these indicate the initial discharge voltage of the lead-coated carbon material formed by the solvent method is high, and the discharge platform is also high, this indicates that the stability of the material is high, and a stable output can be achieved at a high voltage, in addition, the first discharge specific capacity is 73.0 mAh/g after reaching the cutoff voltage (1.70 V), and the first discharge specific capacity of the the physical grinding compared material is 57.24 mAh/g. Comparing the discharge specific capacity of the two materials after reaching the cut-off voltage, the performance of the lead-coated sweet sorghum stalk-based carbon material prepared by the solvent method had been improved by 27.53%.\u003c/p\u003e\n\u003ch3\u003e(2) Cycle life analysis\u003c/h3\u003e\n\u003cp\u003eFinally, the lead paste containing lead-coated sweet sorghum stalk-based carbon material was assembled into a simulated lead carbon battery, and the Neware BTS high-precision battery test system (CT-48-5V 20A) was used after the battery was fully charged, the battery cycle life test of lead-coated sweet sorghum stalk-based carbon material(a) and physical grinding compared material(b) were performed, and the results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec36\" class=\"Section2\"\u003e \u003ch2\u003e(Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e)\u003c/h2\u003e \u003cp\u003eThe capacity of the negative electrode materials prepared by different methods was different after 150 cycles, the specific capacity retention ratio of the lead-coated sweet sorghum stalk-based carbon material was 71.8%, and the specific capacity retention ratio of the physical grinding compared material was only 57.5%.\u003c/p\u003e \u003cp\u003eIn summary, assembled batteries containing lead-coated sweet sorghum stalk-based carbon material has better charge and discharge efficiency and cycle performance. This is mainly due to the better interfacial compatibility between the sweet sorghum stalk-based carbon material and the negative active material lead in the lead-coated carbon material prepared by the solvent method, so that the utilization ratio of the active material is greatly improved, and thus the specific capacity is high and the cycle performance is good.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe lead-coated sweet sorghum stalk-based carbon material was successfully prepared by solvent method with sweet sorghum stalk as carbon source, it was applied to lead-carbon battery, the lead-carbon battery consisting of lead-coated sweet sorghum stalk-based carbon material was tested by a charge and discharge device, which showed that the first discharge specific capacity was 73.0 mAh/g, and the capacity retention after 150 cycles was 71.8%. The characteristic of the lead-coated sweet sorghum stalk-based carbon material is that the interface resistance between the carbon material and the metal lead was reduced, and the conductive network constructed in the anode material increases the conductivity of the negative material and improved the utilization ratio of the active material, thereby improving the capacity of lead carbon battery. Carbon materials prepared from sweet sorghum stalks partially replaced the active material of lead carbon battery, which not only improved the comprehensive utilization degree of sweet sorghum stalks, but also applies the modification of sweet sorghum stalk-based carbon material to batteries, which has potential significance.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eCredit author statementQiuqun Liang: investigation; validation; writing-original draft. Xiaoqi Lan: supervision; review.Zheng Liu: writing-review \u0026amp; editing; supervision.Junjie Ma: investigation validation; design. Guo-Cheng Han: conceptualization; writing-review \u0026amp; editing; supervision. Hao Wang: investigation validation; supervision; review.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eWe gratefully acknowledge the financial support afforded by the following organizations: the National Natural Science Foundation of China (No. 52004076, 61661014), the Nature Science Foundation of Guangxi Province (No. 2018GXNSFBA281114, 2020GXNSFAA297054, 2018GXNSFAA281198, 2018GXNSFBA281135), and finally, Guangxi One Thousand Young and Middle-aged College and University Backbone Teachers Cultivation Program.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eKaabeche A, Bakelli Y(2019) Renewable hybrid system size optimization considering various electrochemical energy storage technologies. 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J Power Sources 15: 380\u0026ndash;399.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"ionics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Ionics](https://www.springer.com/journal/11581) ","snPcode":"11581","submissionUrl":"https://mc.manuscriptcentral.com/ionics","title":"Ionics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Sweet sorghum stalk, carbon material, Coated, Lead carbon battery, Negative material","lastPublishedDoi":"10.21203/rs.3.rs-4881412/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4881412/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eSweet sorghum stalk can be used to prepare carbon materials and used in lead carbon battery negative materials. In this work, the sweet sorghum stalk was pretreated with 5 wt.% H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e, after heated at 550℃ for 105 min, lead-coated sweet sorghum stalk-based carbon materials were prepared by the solvent method, and their electrochemical performance were measured by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), as well as BET test, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray powder diffraction spectrum (XRD) methods. The negative electrode materials contained lead-coated sweet sorghum stalk-based carbon material and physical grinding compared material were assembled into simulated lead-carbon batteries, the charge-discharge tester was used to test their first charge-discharge curves and cycle life curves, the first discharge specific capacity of two kinds materials were 73.0 mAh/g and 57.24 mAh/h, with 71.8% and 57.5% of capacity retention ratios after 150 cycles, respectively, shown that the simulated lead-carbon battery with new prepared carbon material exhibits better electrochemical performance.\u003c/p\u003e","manuscriptTitle":"Preparation of lead-coated sweet sorghum stalk-based carbon material and its electrochemical performance","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-09-06 12:46:47","doi":"10.21203/rs.3.rs-4881412/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-10-03T05:10:31+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-29T17:32:52+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"9625803246726520462450643754618595716","date":"2024-09-24T12:13:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"116493092547722084797561287591027472090","date":"2024-09-23T19:59:50+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-04T09:38:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"69520691977352365154515032188723960289","date":"2024-08-14T17:24:27+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-08-12T16:55:24+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-08-12T05:11:13+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-08-12T05:11:11+00:00","index":"","fulltext":""},{"type":"submitted","content":"Ionics","date":"2024-08-08T13:28:27+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"ionics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Ionics](https://www.springer.com/journal/11581) ","snPcode":"11581","submissionUrl":"https://mc.manuscriptcentral.com/ionics","title":"Ionics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"db436c77-76f1-4cac-9a3c-233b3d8f4d96","owner":[],"postedDate":"September 6th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-12-07T11:23:18+00:00","versionOfRecord":[],"versionCreatedAt":"2024-09-06 12:46:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4881412","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4881412","identity":"rs-4881412","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}