Preparation and Electrochemical Stabilities Study of Graphene/Polyaniline Composites with Polylactic Acid as Biodegradable Adhesive

Preparation and Electrochemical Stabilities Study of Graphene/Polyaniline Composites with Polylactic Acid as Biodegradable Adhesive | 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 and Electrochemical Stabilities Study of Graphene/Polyaniline Composites with Polylactic Acid as Biodegradable Adhesive Huimin Liang, Tong Lin, Jianzhong Li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4261310/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Conductive polymer polyaniline (PANI) is a hot research topic in pseudocapacitor electrode materials due to its advantages of low preparation cost and high specific capacitance. In this work, PANI and graphene/polyaniline composites (Gr/PANI) were prepared by in-situ chemical polymerization. Biodegradable polymer polylactic acid (PLA), as adhensive of electrode material for supercapacitor was used to replace the traditional adhensive polyvinylidene fluoride (PVDF). The morphology and structure of the materials were characterized by SEM and FTIR. Electrochemical behavior was performed by galvanostrotic charge-discharge (GCD), cyclic voltamphe (CV). Results showed PANI compounded with 50 mg graphene (P-50) exhibit excellent electrochemical behavior. The specific capacitance of P-50/PVDF (348.1 F/g at current density of 0.5 A/g) was 27.8% higher than that of undoped PANI. The specific capacitance maintance of P-50/PLA (71.1% content) was 14.4% less than that of P-50/PVDF (85.5%) after 500 number cycles. In addition, the influence of PLA degradation of 90 days on the electrochemical performance of electrode material was studied. Results showed that the specific capacitance at 1 A/g current density decreased from 232.2 F/g to 166.8 F/g after 90 days, compared with that with PVDF from 303 F/g to 274 F/g, The reduction was 18.5%, and it revealed that the PLA may be used in energy storage devices as degradable adhesive. Graphene/polyaniline composites Polylactic acid Biodegradable supercapacitors Conductive polymer Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Introduction With the rapid development of society and the massive consumption of non-renewable energy, the energy crisis has attracted worldwide attention [ 1 ]. In addition, the use of fossil energy will produce greenhouse gases and lead to global warming, therefore, it is imperative to develop renewable, green and clean energy storage devices [ 2 , 3 ]. Energy storage batteries [ 4 , 5 ] and supercapacitors [ 6 , 7 ] have been widely studiedand applied increasingly widespread for their advantages of energy storage performance[ 8 , 9 ]. Typically, supercapacitors with many advantages [ 10 ] such as fast charge and discharge, long service life, wide temperature range [ 11 ] has been widely used in manyareas [ 12 ]. However, it is very difficult to recycle capacitors for the use of non-degradable polymer, such as polyvinylidene fluoride (PVDF), as binder of the electrode materials. The extensive application of capacitors may cause serious environmental pollution. Polyaniline (PANI), a common conductive polymer, is an ideal electrode material for pseudocapacitors because of its simple preparation method, high yield and large specific capacitance [ 13 , 14 ]. There are three different oxidation states of PANI, namely, the oxidation state, the reduction state and the half-oxidation-half-reduction state [ 15 ]. It is worth noting that only PANI in the half-oxidation-half-reduction state can be redox [ 16 ]. Graphene, with its large theoretical specific capacitance and high specific surface area, can be used as electric double-layer capacitor electrode to provide capacitance through the double layers of the electrode-electrolyte interface [ 17 , 18 ]. It has been shown that excellent electrochemical properties can be obtained by combining graphene with PANI [ 19 ], in which can inhibit the structure fracture caused by volume change during charging and discharging [ 20 ]. The grapheme can improve the electrochemical performance of PANI [ 21 ]. Li et al. prepared graphene/polyaniline composites modified with carbon nanodots by supramolecular in situ self-assembly technique, which reduced the agglomeration of graphene and had low charge transfer resistance, and presentable cycling performance [ 22 ]. Polylactic acid (PLA), a typical kind of biodegradable polymer, has been used as the matrix of functional materials [ 23 , 24 ], which has attracted much attention [ 25 ]. In recent years, there have been many studies on the preparation of green flexible supercapacitors (SC) using PLA as polymer substrate [ 26 ]. Wang et al. designed a kind of self-supporting composite film electrode by using the polylactic acid/carbon nanotube porous polymer nanocomposite films as the conductive degradable substrate of supercapacitor, which has excellent mechanical strength, good cycle stability and specific capacitance of 510.3 F/g in 1.0 mol/L sulphuric acid electrolyte [ 27 ]. Due to its biodegradable and biocompatibility properties, PLA has potential for short-term applications and is expected to reduce e-waste contamination [ 28 ]. In this work, graphene/ PANI composite was prepared by in-situ chemical polymerization using APS as oxidant in the presence of hydrochloric acid. Electrodes of graphene/PANI were prepared using PLA or PVDF as adhensive of the active materials. The capacitance performance of grapheme/PANI was studied. Further, the effect of PLA degradation of 90 days on capacitance performance was discussed, compared with that using PVDF as adhensive. Result show that PLA is a worthwhile application choice as adhensive in capacitor to replace traditional material. Materials and methods Materials Aniline (AN) was purchased from Damao chemical reagent factory in Tianjin, and distilled under reduced pressure before used. Graphene was provided by Daewoo Chemical Co., Ltd. PLA was prepared by ring-opening polyerization of L-lactide with M w =185 kDa and PDI = 1.85 in the laboratory. Ammonium persulfate (APS) was obtained from Tianjin BASF Chemical Co., Ltd. N-Methyl pyrrolidone (NMP, 99%) was supplied by Tianjin Opusheng Chemical Co., Ltd.The other reagents used were all analytical pure. Synthesis of PANI Polyaniline was synthesized by in-situ chemical oxidation polymerization of AN. In the presence of HCl, the dark green product polyaniline was obtained by using APS as oxidant, the amount of AN and APS substance was 1:1, and the reaction temperature was 0℃. In a typical procedure, 0.05 mol APS was dissolved in 100 mL HCl (1M) to obtain solution A. Then 0.05 mol AN mixed with 50 mL HCl (2M), after mixing for 30 min, solution B was obtained. Solution B was stirred by magnetic force in ice bath, after the temperature was stabilized at 0℃, solution A was added slowly, controlled to be added within 1 h, and then continued to react in ice bath for 6 h. After the end of the reaction, the product was filtered in vacuum, washed repeatedly with water and anhydrous ethanol until the filtrate became colorless, then transferred to a vacuum drying chamber and dried in vacuum at 80℃ for 12 hours. Finally, the dark green product polyaniline (PANI) was obtained. Synthesis of graphene/PANI nanocomposites The preparation process of graphene/PANI composites is similar to that of PANI. 20 mg, 50 mg and 80 mg of graphene (Gr) were added into 0.05 mol AN respectively, and mixed by ultrasonic dispersion for 30 min, then added 50 mL HCl (2M), continued ultrasonic mixing for 30 min to obtain solution C. Replace solution B with solution C, and repeat the operation described above. The products with different content of Gr were named P-20, P-50 and P-80. Preparation of electrodes The pre-processing of nickel foam (NF): Cut the NF into 1 × 2cm, then put it into 1 mol/L HCl, distilled water and absolute ethanol to wash by ultrasonic, put it into the oven and dry. Processing the carbon cloth in the same way. Preparation of electrode with PVDF as binder Mixed the active substance, PVDF and acetylene black with a mass ratio of 8:1:1, put it into the agate mortar, add an appropriate amount of N-Methyl pyrrolidone (NMP), grind for half an hour to obtain a uniform black electrode slurry, coat it on the weighed NF, put it into a vacuum drying oven, 110℃ dry for 12 hours. The dry electrode was taken out and weighed again after pressing under 10 Mpa. The mass of the active material was calculated according to the difference of the mass before and after the NF. The coating area is 1 cm 2 and the mass of active substance is about 4 mg. Preparation of electrode with PLA as binder A solution of 0.025 g/mL was prepared by dissolving PLA in dichloromethane (DCM) and adding N, N-Dimethylformamide (DMF) of the same volume. Three parts of PANI (P-50) and acetylene black were added with different amount of PLA(0.005 g, 0.01 g and 0.02 g) respectively to prepare PANI (P-50), acetylene black and PLA with mass ratios of 8:1:1, 8:1:2 and 8:1:4, grind and mix well and follow up with operation as above to prepare electrodes. Characterization of electrode materials The prepared samples were fixed on the sample stand by conductive adhesive, and the surface morphology of the samples was observed under the Scanning electron microscope (JSM-IT500) after gold spraying treatment. Chemical analysis of the materials was carried out using potassium bromide tablet-pressing and Fourier transform infrared spectroscopy (Nicolet IS10) at wavelengths ranging from 400 nm to 4000 nm. The crystallinity of the nanocomposites were assessed by X-Ray polycrystalline diffractometer (XRD, D8ADVANCE) with Cu-Kα radiation (λ =1.54 A) at 40 kV and 40mA current with 2θ ranging from 10° to 90°, step size 0.02°, and counting time 0.1 s. Electrochemical performance test The electrochemical performance of the material was tested in 1M Na 2 SO 4 electrolyte using three-electrode mode of Chenhua electrochemical workstation (EC240F), platinum plate as the counter electrode electrode, Ag/AgCl electrode as the reference electrode and active substance as the working electrode. The specific capacitance of single electrode can be calculated by cyclic voltammetry (CV) [ 29 ] curve and constant current charge-discharge (GCD) [ 30 ] curve. The formula was as follows: $${C}_{p}=\frac{A}{2\varDelta Vmk}$$ 1 $${C}_{m}=\frac{I\times \varDelta t}{m\times \varDelta V}$$ 2 Where A is the area enclosed by the CV curve, AV; ΔV is the voltage of the discharge curve, V; m is the mass of the active substance on the electrode, g; K is the scanning rate, v/s; I is the discharge current,A; Δt is the discharge time, s; P and Cm are specific capacitance, F/g. It should be noted that the cyclic stability of the electrode was determined by Neware (DW-P530-1ACDF) in 0.5M sulphuric acid electrolyte, where the electrode material was coated on carbon cloth and the calomel electrode was used as the reference electrode instead of the Ag/AgCl electrode. Results and discussion SEM analysis It can be seen from Fig. 1 a that the non-graphene doped PANI has a nearly spherical structure, and the agglomeration phenomenon is serious. The PANI is highly interconnected, closely spaced, and has fewer voids. Scanning image of P-20 with 20 mg of graphene is depicted in Fig. 1 b. Compared with PANI, P-20 has a clearer spherical structure, lower cohesion and higher specific surface area. Figure 1 c is a scanned image of P-50 with 50 mg of graphene. Graphene provides more active sites for PANI, which is easier to shape, growing into nanorods of PANI. P-50 has a larger voidage, a higher specific surface area, which facilitates electrolyte penetration and increases the contact area between the electrode and the electrolyte. As we can see in Fig. 1 d, with the increase of the content of graphene, the material agglomerates again and the voidage decreases. It can be seen tha adding an appropriate amount of graphene can obtain the ideal product of morphology. FTIR analysis Figure 2 shows the FTIR spectra of PLA, PANI, P-50 and P-50 + PLA. The strong C = O absorption peak at 1759 cm − 1 can be seen in the PLA spectra [ 31 ]. The C-H stretching vibration of 2947 cm − 1 is a common characteristic peak of PLA, and the methyl group moves to higher wavenumber due to the absorption action of neighboring carbonyl and oxygen atoms. The absorption peak of 1454cm − 1 belongs to C-H bending vibration. The absorption peak at 1184cm − 1 is due to C-O stretching vibration, and the absorption peak at 1091cm − 1 is due to in-plane bending of O-H bond. In the PANI, P-50 and P-50 + PLA spectra, the absorption peaks at 1666cm − 1 , 1135cm − 1 and 1106cm − 1 are from the C = C skeleton vibration on the benzene ring, the C-N stretching vibration absorption peak in quinone structure and benzene structure, respectively [ 32 ]. In the P-50 + PLA spectrum, it can be seen that the C = 0 absorption peak is significantly reduced, which can be attributed to the impact of the benzene ring in polyaniline on it, which makes its absorption frequency lower. XRD analysis The XRD patterns of PANI, P-50 and P-50 + PLA were as shown in Fig. 3 . The wide peak of 10–30° shows the low crystallinity of polyaniline. As can be seen from the figure, the diffraction peaks at 2θ=14.8°, 20.2°, 25.3° belong to the amorphous structure of polyaniline. The diffraction peak of 2θ ༝20.2° is generated by the amorphous PANI, corresponding to the parallel (100) plane of the PANI backbone, and the diffraction peak of 2θ༝25.3° corresponds to the orthogonal (110) plane of the backbone, indicating that PANI and P-50 has superior regularity [ 33 , 34 ]. The diffraction peak of P-50 at 2θ༝26° comes from the typical graphite structure, which is the (002) plane of the hexagonal graphite carbon, illustrating the successful recombination of graphene [ 22 ]. The diffraction peak of P-50 + PLA at 2θ༝16 belongs to the amorphous structure of PLA, which confirms the successful addition of PLA[ 34 ]. Electrochemical performance analysis The charge-discharge curves of PANI, P-20, P-50 and P-80 in 1M Na 2 SO 4 electrolyte under the potential window of -0.4V to 0.6V at different current as shown in Fig. 4 . It can be seen that the charge and discharge of all samples are not straight lines, which indicates the existence of pseudocapacitance behavior. The discharge time decreases with the increase of current density. The charge-discharge curves of all samples are almost the same when the current density is changed, which shows that the electrochemical properties of the materials are stable in the current density range of 0.5-5A/g. At the current density of 1A/g, the discharge time of P-50 was the longest, which indicated that the specific capacitance of PANI was increased by adding proper amount of graphene. According to the formula (2), the specific capacitance of the sample at different current densities is calculated and the ratio curve of Fig. 5 a is obtained. At the current density of 0.5 A/g, the specific capacitance of P-50 is 348.1 F/g, which is 27.8% higher than that of PANI (272.4 F/g). It can be seen from the figure that the specific capacitance of P -50 is larger at different current densities, indicating that the electrochemical properties of PANI are improved by adding proper amount of graphene. In order to investigate the electrochemical behavior of the electrode materials, the cyclic voltammetric curves of the samples were determined at a sweep rate of 0.01 v/s at a potential window of -0.4 -1.2 V, as shown by Fig. 5 b. It can be found that the redox peak of PANI become more obvious with the increase of the content of graphene from 0 to 50 mg. However, when the content of graphene increases to 80 mg, the redox peak appears a significant deviation and the area also decreases. This phenomenon can be attributed to the excessive graphene cover up the good electrochemical properties of PANI. According to formula (1), it can be inferred that under the same potential window and scanning speed, the larger the area surrounded by the CV curve is, the larger the capacitance of the sample with the same quality of the active substance. In addition, Fig. 5 b further confirmed the pseudocapacitance property of PANI materials. Figure 6 and Fig. 7 are GCD curves and magnification diagrams of electrode materials with PLA as binder. It can be seen that the charging and discharging time of PANI and P-50 decreased with the increase of PANI content under different currents, when the mass ratio of sample, acetylene black and PLA is 8:1:1, the specific capacitance is higher. In addition, as the content of PLA increases, there is no new discharge platform appears in the GCD curve, indicating that PLA does not redox in this system and does not provide pseudo-capacitance. The sample with PLA as adhensive has obvious voltage drop, compared with that of PVDF as adhensive, in the same charge-discharge interval and current density. It is due to the addition of PLA increases the contact resistance between the electrode and the electrolyte, which leads to the decrease of the electrochemical performance of the electrode. The cyclic voltamphere of PANI and P-50 with different PLA at 0.01 V/s is depicted in Fig. 8 . It can be observed from the graph that the area enclosed by the CV curve decrease with the increase of PLA content. It indicated that the specific capacitance decrease and the reduction potential of electrode materials with different proportions does not change significantly. When 0.02g PLA was added, the redox peak intensity of PANI and P-50 decreased, which was due to the excessive PLA hindering the contact between electrode material and electrolyte, and the reduction of electrolyte ions involved in the electrochemical reaction, the portion of the electrode active material utilized is reduced, resulting in a smaller specific capacitance. The cyclic stability of P-50 + PLA and P-50 + PVDF was tested with a voltage window of 0.01-0.6V in 0.5 M H 2 SO 4 solution, results as shown in Fig. 9 . Curves of a 1 , a 2 (b 1 , b 2 ) were the voltage-capacity curves of P-50 + PLA (P-50 + PVDF) initial and after 500 cycles, respectively. As can be seen from the graph, the specific capacity of P-50 + PLA decreased from 50 mAh/g to 36 mAh/g, and the capacitance retention rate was 71%, while the specific capacity of P-50 + PVDF decreased from 62 mAh/g to 53 mAh/g, and the capacitance retention rate was 86%. From this, it can be seen that the electrode with PLA as binder is not as stable as that with PVDF as binder, but it still has a considerable specific capacity after 500 charge-discharge cycles. Degradation behavior analysis of P-50 + PLA/P-50 + PVDF The P-50, acetylene black and PLA samples (P-50 + PLA) with mass ratio of 8:1:1 and the P-50, acetylene black and PVDF samples (P-50 + PVDF) with mass ratio of 8:1:1 were selected as control, the electrochemical properties of P-50 + PLA during degradation were studied. Several electrode plates were prepared in the same batch and put into 1M Na 2 SO 4 electrolyte. The GCD curves were measured at different time intervals, the specific capacitance was calculated, and the change of specific capacitance with time was recorded, the results are shown in Fig. 10 . In Fig. 10 a, it could be observed that the capacitance value of the sample with PVDF as binder was basically stable at 300 F/g for the first three days, with a slight increase to 326.8F/g on the fourth day, followed by a gradual decrease. The values measured at intervals of 20 and 30 days did not fluctuate much. After 90 days, the specific capacitance decreased by about 10%, indicating that the electrochemical properties of electrode materials with PVDF as binder were stable. After replacing PVDF with PLA, the specific capacitance of the electrode material decreased, and on the third day, the P-50 + PLA's specific capacitance increased, which is due to the electrolyte immersion for a long time, so that the electrode and electrolyte fully contact, participate in the electrode reaction of active substances increased. On the fourth day, the specific capacitance of P-50 + PLA decreased rapidly, and then decreased slowly with time. After 90 days, the specific capacitance of P-50 + PLA decreased by 28%, indicating that PLA gradually degraded over time, which has affected the electrochemical properties of electrode materials. Figure 10 b shows the CV curve after 90 days of placement of the electrode material. As can be seen from Fig. 10 b, P-50 still has obvious redox peak and pseudocapacitance, but the area enclosed by the CV curve is reduced, this is corresponding to the degradation of the electrode material, and the degradation behavior of the electrode with PLA as adhensive is further verified from the side. Conclusions To sum up, grapheme/PANI composites and PANI were successfully synthesized by in situ chemical oxidation. The SEM images show that the P-50 nanorods have higher specific surface area and higher porosity, which lead to more active materials are involved in the electrochemi cal reaction. Instead of the traditional binder PVDF, the biodegradable PLA was used, and the electrode material remained the same Faraday redox.With the increase of PLA content, the resistance between electrode material and electrolyte increases, and the specific capacitance decreases. The P-50 + PVDF kept good stability, and the capacitance drops slightly after 90 days, while the specific capacitance of P-50 + PLA decreased by 28% after 90 days due to the degradation of PLA. Based on the PLA of environmental protection, this paper provides a new idea for the research of environmentally friendly degradable super capacitors. Declarations Author Contribution All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Liang. The first draft of the manuscript was written by Liang and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. References Goel A, Mashangva TT, Garg A et al (2023) Synthesis of NiCo2O4/rGO/PANI ternary nanocomposite for electrochemical performance and impact of doping on pure PANI. 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Journal of Inorganic and Organometallic Polymers and Materials 32(8):3093-3105. http://doi.org/10.1007/s10904-022-02335-8 Bibi A, Shakoor A, Niaz NA et al (2023) Enhanced solar-driven photocatalytic and photovoltaic performance of polymer composite containing carbon black and calcium titanate nanoparticles. Polymer Bulletin. http://doi.org/10.1007/s00289-023-05108-6 Tomomi K, Akira Kk, Kazukiyo N (2008) Characterization and gas transport properties of poly (lactic acid) blend membranes. Desalination. 234 (1-3): 212–220. http://doi.org/ 10.1016/j.desal.2007.09.088 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-4261310","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":291152089,"identity":"d05e90a1-598e-4644-be33-21ed3c6d033e","order_by":0,"name":"Huimin Liang","email":"","orcid":"","institution":"Qingdao Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Huimin","middleName":"","lastName":"Liang","suffix":""},{"id":291152090,"identity":"e48ac1ee-0e22-46c1-868b-dbacc7d046be","order_by":1,"name":"Tong Lin","email":"","orcid":"","institution":"Qingdao Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Tong","middleName":"","lastName":"Lin","suffix":""},{"id":291152091,"identity":"3d710a09-bd91-4407-bb03-5499857f816c","order_by":2,"name":"Jianzhong Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAs0lEQVRIiWNgGAWjYBACxgYexgMMDDY8/PwNxGthAGpJk5GccYBoe8BaDtsYNCQQqYG5/+yBAx8qzvMYMBxg/PAxhyiHnUs4OOPMbR5z5gZmyZnbiNHS2GNwmLftNo9lwwE2Zl6itDTzGBz+++8cj8GBBGK1tAG1MDYcIEVLD4/BwZ5jyTySMw42E+cXw/4zhg9+1NjZ8/M3H/zwkSgtDQgLG3CqQgHyxCkbBaNgFIyCEQ0AeIk5M4MbjyUAAAAASUVORK5CYII=","orcid":"","institution":"Qingdao Agricultural University","correspondingAuthor":true,"prefix":"","firstName":"Jianzhong","middleName":"","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2024-04-13 09:44:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4261310/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4261310/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":54837503,"identity":"ed498bce-f74f-4ce3-86ae-6b499f3a44ac","added_by":"auto","created_at":"2024-04-17 13:00:12","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":3252603,"visible":true,"origin":"","legend":"\u003cp\u003eSEM morphological images of (\u003cstrong\u003ea\u003c/strong\u003e) PANI, (\u003cstrong\u003eb\u003c/strong\u003e) P-20, (\u003cstrong\u003ec\u003c/strong\u003e) P-50 and (\u003cstrong\u003ed\u003c/strong\u003e) P-80.\u003c/p\u003e","description":"","filename":"Figure.1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/3b74597eb5c58dd9f71031c9.jpg"},{"id":54837974,"identity":"0c0df9b1-6dc9-4710-a28b-4cf6164286d5","added_by":"auto","created_at":"2024-04-17 13:08:13","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":574948,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra of PLA, PANI, P-50 and P-50+PLA\u003c/p\u003e","description":"","filename":"Figure.2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/41fe3f5f9e8911f71f1c2afb.jpg"},{"id":54837975,"identity":"4e332596-f396-4b91-bc62-4cd024a0d968","added_by":"auto","created_at":"2024-04-17 13:08:13","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":425004,"visible":true,"origin":"","legend":"\u003cp\u003eXRD spectra of PANI, P-50 and P-50+PLA\u003c/p\u003e","description":"","filename":"Figuer.3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/92fc790c91202f296c3f3ac7.jpg"},{"id":54837504,"identity":"83d67616-084e-4dc0-8d5f-d1ad111e4589","added_by":"auto","created_at":"2024-04-17 13:00:13","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":886907,"visible":true,"origin":"","legend":"\u003cp\u003eGCD curves of (\u003cstrong\u003ea\u003c/strong\u003e) PANI, (\u003cstrong\u003eb\u003c/strong\u003e) P-20, (\u003cstrong\u003ec\u003c/strong\u003e) P-50 and (\u003cstrong\u003ed\u003c/strong\u003e) P-80 at different current densities of 0.5, 1.0, 2.0, and 5.0 A g\u003csup\u003e−1\u003c/sup\u003e\u003c/p\u003e","description":"","filename":"Figure.4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/def46923357c448ddf85fcff.jpg"},{"id":54837512,"identity":"ee8cc41b-983e-4b9d-96d2-c90b01875eef","added_by":"auto","created_at":"2024-04-17 13:00:13","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":554283,"visible":true,"origin":"","legend":"\u003cp\u003e(\u003cstrong\u003ea\u003c/strong\u003e) The specific capacitances of the P-20, P-50, P-80, and PANI at different current densities of 0.5, 1.0, 2.0, and 5.0 A g\u003csup\u003e−1\u003c/sup\u003e. (\u003cstrong\u003eb\u003c/strong\u003e) CV curves of the P-20, P-50, P-80, and PANI at a scan rate of 0.01V s\u003csup\u003e−1 \u003c/sup\u003ein 1 mol L\u003csup\u003e−1\u003c/sup\u003e Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e solution.\u003c/p\u003e","description":"","filename":"Figure.5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/9b6eb720a73f17e252d6027d.jpg"},{"id":54837506,"identity":"9d2b524b-eec4-4eae-9425-62b05f7da7df","added_by":"auto","created_at":"2024-04-17 13:00:13","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":903594,"visible":true,"origin":"","legend":"\u003cp\u003eGCD curves of (a) PANI+0.005PLA, (b) PANI+0.010PLA and (c) PANI+0.020PLA at different current densities of 0.5, 1.0, 2.0, and 5.0 A g\u003csup\u003e−1\u003c/sup\u003e. (d)The specific capacitances of the PANI+0.005 PLA， \u0026nbsp;PANI+0.010PLA and PANI+0.020PLA at different current densities of 0.5, 1.0, 2.0,and 5.0 A g\u003csup\u003e−1\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"Figure.6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/d8a863ee1c1f9915130895b2.jpg"},{"id":54838449,"identity":"0bc0396b-bb22-4a6d-b8d9-69801c86cce2","added_by":"auto","created_at":"2024-04-17 13:16:13","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":933378,"visible":true,"origin":"","legend":"\u003cp\u003eGCD curves of (\u003cstrong\u003ea\u003c/strong\u003e) P-50+0.005PLA, (\u003cstrong\u003eb\u003c/strong\u003e) P-50+0.010PLA and (\u003cstrong\u003ec\u003c/strong\u003e) P-50+0.020PLA at different current densities of 0.5, 1.0, 2.0, and 5.0 A g\u003csup\u003e−1\u003c/sup\u003e. (\u003cstrong\u003ed\u003c/strong\u003e) The specific capacitances of the P-50+0.005 PLA, P-50+0.010PLA and P-50+0.020PLA at different current densities of 0.5, 1.0, 2.0 and 5.0 A g\u003csup\u003e−1\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"Figure.7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/eb653fd29a772d8967324f10.jpg"},{"id":54837511,"identity":"e6704f0f-b237-44d0-ac16-eca4014245a0","added_by":"auto","created_at":"2024-04-17 13:00:13","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":604812,"visible":true,"origin":"","legend":"\u003cp\u003e(\u003cstrong\u003ea\u003c/strong\u003e), (\u003cstrong\u003eb\u003c/strong\u003e) CV curves of materials at a scan rate of 0.01V s\u003csup\u003e−1 \u003c/sup\u003ein 1 mol L\u003csup\u003e−1\u003c/sup\u003e Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e solution.\u003c/p\u003e","description":"","filename":"Figure.8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/a47d2b54436048a5c2e050bb.jpg"},{"id":54837509,"identity":"ee800604-cbce-4ea4-8d2d-7bdfbeb6c751","added_by":"auto","created_at":"2024-04-17 13:00:13","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":578470,"visible":true,"origin":"","legend":"\u003cp\u003eThe cyclic stability of P-50+PLA and P-50+PVDF\u003c/p\u003e","description":"","filename":"Figure.9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/b05314136bd6cb98487addeb.jpg"},{"id":54837510,"identity":"590833d8-8a46-4da5-9059-8fe3b345eb79","added_by":"auto","created_at":"2024-04-17 13:00:13","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":548021,"visible":true,"origin":"","legend":"\u003cp\u003eThe specific capacitance of P-50+PANI, P-50+PLA changes with time (a). CV curves of P-50+PANI, P-50+PLA (b).\u003c/p\u003e","description":"","filename":"Figure.10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/be6815fd3c522300dd50b254.jpg"},{"id":55590772,"identity":"ca0c3bec-fe96-456c-922c-99b84996680a","added_by":"auto","created_at":"2024-04-30 09:35:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1510708,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4261310/v1/3d57622b-311f-42b3-add8-47de4907e37f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Preparation and Electrochemical Stabilities Study of Graphene/Polyaniline Composites with Polylactic Acid as Biodegradable Adhesive","fulltext":[{"header":"Introduction","content":"\u003cp\u003eWith the rapid development of society and the massive consumption of non-renewable energy, the energy crisis has attracted worldwide attention [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In addition, the use of fossil energy will produce greenhouse gases and lead to global warming, therefore, it is imperative to develop renewable, green and clean energy storage devices [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Energy storage batteries [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] and supercapacitors [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] have been widely studiedand applied increasingly widespread for their advantages of energy storage performance[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Typically, supercapacitors with many advantages [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] such as fast charge and discharge, long service life, wide temperature range [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] has been widely used in manyareas [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. However, it is very difficult to recycle capacitors for the use of non-degradable polymer, such as polyvinylidene fluoride (PVDF), as binder of the electrode materials. The extensive application of capacitors may cause serious environmental pollution.\u003c/p\u003e \u003cp\u003ePolyaniline (PANI), a common conductive polymer, is an ideal electrode material for pseudocapacitors because of its simple preparation method, high yield and large specific capacitance [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. There are three different oxidation states of PANI, namely, the oxidation state, the reduction state and the half-oxidation-half-reduction state [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. It is worth noting that only PANI in the half-oxidation-half-reduction state can be redox [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Graphene, with its large theoretical specific capacitance and high specific surface area, can be used as electric double-layer capacitor electrode to provide capacitance through the double layers of the electrode-electrolyte interface [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. It has been shown that excellent electrochemical properties can be obtained by combining graphene with PANI [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], in which can inhibit the structure fracture caused by volume change during charging and discharging [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The grapheme can improve the electrochemical performance of PANI [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Li et al. prepared graphene/polyaniline composites modified with carbon nanodots by supramolecular in situ self-assembly technique, which reduced the agglomeration of graphene and had low charge transfer resistance, and presentable cycling performance [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePolylactic acid (PLA), a typical kind of biodegradable polymer, has been used as the matrix of functional materials [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], which has attracted much attention [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. In recent years, there have been many studies on the preparation of green flexible supercapacitors (SC) using PLA as polymer substrate [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Wang et al. designed a kind of self-supporting composite film electrode by using the polylactic acid/carbon nanotube porous polymer nanocomposite films as the conductive degradable substrate of supercapacitor, which has excellent mechanical strength, good cycle stability and specific capacitance of 510.3 F/g in 1.0 mol/L sulphuric acid electrolyte [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDue to its biodegradable and biocompatibility properties, PLA has potential for short-term applications and is expected to reduce e-waste contamination [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. In this work, graphene/ PANI composite was prepared by in-situ chemical polymerization using APS as oxidant in the presence of hydrochloric acid. Electrodes of graphene/PANI were prepared using PLA or PVDF as adhensive of the active materials. The capacitance performance of grapheme/PANI was studied. Further, the effect of PLA degradation of 90 days on capacitance performance was discussed, compared with that using PVDF as adhensive. Result show that PLA is a worthwhile application choice as adhensive in capacitor to replace traditional material.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMaterials\u003c/h2\u003e \u003cp\u003eAniline (AN) was purchased from Damao chemical reagent factory in Tianjin, and distilled under reduced pressure before used. Graphene was provided by Daewoo Chemical Co., Ltd. PLA was prepared by ring-opening polyerization of L-lactide with \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ew\u003c/em\u003e\u003c/sub\u003e=185 kDa and PDI\u0026thinsp;=\u0026thinsp;1.85 in the laboratory. Ammonium persulfate (APS) was obtained from Tianjin BASF Chemical Co., Ltd. N-Methyl pyrrolidone (NMP, 99%) was supplied by Tianjin Opusheng Chemical Co., Ltd.The other reagents used were all analytical pure.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis of PANI\u003c/h2\u003e \u003cp\u003ePolyaniline was synthesized by in-situ chemical oxidation polymerization of AN. In the presence of HCl, the dark green product polyaniline was obtained by using APS as oxidant, the amount of AN and APS substance was 1:1, and the reaction temperature was 0℃. In a typical procedure, 0.05 mol APS was dissolved in 100 mL HCl (1M) to obtain solution A. Then 0.05 mol AN mixed with 50 mL HCl (2M), after mixing for 30 min, solution B was obtained. Solution B was stirred by magnetic force in ice bath, after the temperature was stabilized at 0℃, solution A was added slowly, controlled to be added within 1 h, and then continued to react in ice bath for 6 h. After the end of the reaction, the product was filtered in vacuum, washed repeatedly with water and anhydrous ethanol until the filtrate became colorless, then transferred to a vacuum drying chamber and dried in vacuum at 80℃ for 12 hours. Finally, the dark green product polyaniline (PANI) was obtained.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis of graphene/PANI nanocomposites\u003c/h2\u003e \u003cp\u003eThe preparation process of graphene/PANI composites is similar to that of PANI. 20 mg, 50 mg and 80 mg of graphene (Gr) were added into 0.05 mol AN respectively, and mixed by ultrasonic dispersion for 30 min, then added 50 mL HCl (2M), continued ultrasonic mixing for 30 min to obtain solution C. Replace solution B with solution C, and repeat the operation described above. The products with different content of Gr were named P-20, P-50 and P-80.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of electrodes\u003c/h2\u003e \u003cp\u003eThe pre-processing of nickel foam (NF): Cut the NF into 1 \u0026times; 2cm, then put it into 1 mol/L HCl, distilled water and absolute ethanol to wash by ultrasonic, put it into the oven and dry. Processing the carbon cloth in the same way.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of electrode with PVDF as binder\u003c/h2\u003e \u003cp\u003eMixed the active substance, PVDF and acetylene black with a mass ratio of 8:1:1, put it into the agate mortar, add an appropriate amount of N-Methyl pyrrolidone (NMP), grind for half an hour to obtain a uniform black electrode slurry, coat it on the weighed NF, put it into a vacuum drying oven, 110℃ dry for 12 hours. The dry electrode was taken out and weighed again after pressing under 10 Mpa. The mass of the active material was calculated according to the difference of the mass before and after the NF. The coating area is 1 cm\u003csup\u003e2\u003c/sup\u003e and the mass of active substance is about 4 mg.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of electrode with PLA as binder\u003c/h2\u003e \u003cp\u003eA solution of 0.025 g/mL was prepared by dissolving PLA in dichloromethane (DCM) and adding N, N-Dimethylformamide (DMF) of the same volume. Three parts of PANI (P-50) and acetylene black were added with different amount of PLA(0.005 g, 0.01 g and 0.02 g) respectively to prepare PANI (P-50), acetylene black and PLA with mass ratios of 8:1:1, 8:1:2 and 8:1:4, grind and mix well and follow up with operation as above to prepare electrodes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eCharacterization of electrode materials\u003c/h2\u003e \u003cp\u003eThe prepared samples were fixed on the sample stand by conductive adhesive, and the surface morphology of the samples was observed under the Scanning electron microscope (JSM-IT500) after gold spraying treatment.\u003c/p\u003e \u003cp\u003eChemical analysis of the materials was carried out using potassium bromide tablet-pressing and Fourier transform infrared spectroscopy (Nicolet IS10) at wavelengths ranging from 400 nm to 4000 nm.\u003c/p\u003e \u003cp\u003eThe crystallinity of the nanocomposites were assessed by X-Ray polycrystalline diffractometer (XRD, D8ADVANCE) with Cu-Kα radiation (λ =1.54 A) at 40 kV and 40mA current with 2θ ranging from 10\u0026deg; to 90\u0026deg;, step size 0.02\u0026deg;, and counting time 0.1 s.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eElectrochemical performance test\u003c/h2\u003e \u003cp\u003eThe electrochemical performance of the material was tested in 1M Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e electrolyte using three-electrode mode of Chenhua electrochemical workstation (EC240F), platinum plate as the counter electrode electrode, Ag/AgCl electrode as the reference electrode and active substance as the working electrode. The specific capacitance of single electrode can be calculated by cyclic voltammetry (CV) [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] curve and constant current charge-discharge (GCD) [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] curve. The formula was as follows:\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$${C}_{p}=\\frac{A}{2\\varDelta Vmk}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$${C}_{m}=\\frac{I\\times \\varDelta t}{m\\times \\varDelta V}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere A is the area enclosed by the CV curve, AV; ΔV is the voltage of the discharge curve, V; m is the mass of the active substance on the electrode, g; K is the scanning rate, v/s; I is the discharge current,A; Δt is the discharge time, s; P and Cm are specific capacitance, F/g.\u003c/p\u003e \u003cp\u003eIt should be noted that the cyclic stability of the electrode was determined by Neware (DW-P530-1ACDF) in 0.5M sulphuric acid electrolyte, where the electrode material was coated on carbon cloth and the calomel electrode was used as the reference electrode instead of the Ag/AgCl electrode.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eSEM analysis\u003c/h2\u003e \u003cp\u003eIt can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea that the non-graphene doped PANI has a nearly spherical structure, and the agglomeration phenomenon is serious. The PANI is highly interconnected, closely spaced, and has fewer voids. Scanning image of P-20 with 20 mg of graphene is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb. Compared with PANI, P-20 has a clearer spherical structure, lower cohesion and higher specific surface area. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec is a scanned image of P-50 with 50 mg of graphene. Graphene provides more active sites for PANI, which is easier to shape, growing into nanorods of PANI. P-50 has a larger voidage, a higher specific surface area, which facilitates electrolyte penetration and increases the contact area between the electrode and the electrolyte. As we can see in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed, with the increase of the content of graphene, the material agglomerates again and the voidage decreases. It can be seen tha adding an appropriate amount of graphene can obtain the ideal product of morphology.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eFTIR analysis\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the FTIR spectra of PLA, PANI, P-50 and P-50\u0026thinsp;+\u0026thinsp;PLA. The strong C\u0026thinsp;=\u0026thinsp;O absorption peak at 1759 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be seen in the PLA spectra [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The C-H stretching vibration of 2947 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is a common characteristic peak of PLA, and the methyl group moves to higher wavenumber due to the absorption action of neighboring carbonyl and oxygen atoms. The absorption peak of 1454cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e belongs to C-H bending vibration. The absorption peak at 1184cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is due to C-O stretching vibration, and the absorption peak at 1091cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is due to in-plane bending of O-H bond. In the PANI, P-50 and P-50\u0026thinsp;+\u0026thinsp;PLA spectra, the absorption peaks at 1666cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1135cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1106cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are from the C\u0026thinsp;=\u0026thinsp;C skeleton vibration on the benzene ring, the C-N stretching vibration absorption peak in quinone structure and benzene structure, respectively [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. In the P-50\u0026thinsp;+\u0026thinsp;PLA spectrum, it can be seen that the C\u0026thinsp;=\u0026thinsp;0 absorption peak is significantly reduced, which can be attributed to the impact of the benzene ring in polyaniline on it, which makes its absorption frequency lower.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eXRD analysis\u003c/h2\u003e \u003cp\u003eThe XRD patterns of PANI, P-50 and P-50\u0026thinsp;+\u0026thinsp;PLA were as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The wide peak of 10\u0026ndash;30\u0026deg; shows the low crystallinity of polyaniline. As can be seen from the figure, the diffraction peaks at 2θ=14.8\u0026deg;, 20.2\u0026deg;, 25.3\u0026deg; belong to the amorphous structure of polyaniline. The diffraction peak of 2θ ༝20.2\u0026deg; is generated by the amorphous PANI, corresponding to the parallel (100) plane of the PANI backbone, and the diffraction peak of 2θ༝25.3\u0026deg; corresponds to the orthogonal (110) plane of the backbone, indicating that PANI and P-50 has superior regularity [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The diffraction peak of P-50 at 2θ༝26\u0026deg; comes from the typical graphite structure, which is the (002) plane of the hexagonal graphite carbon, illustrating the successful recombination of graphene [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The diffraction peak of P-50\u0026thinsp;+\u0026thinsp;PLA at 2θ༝16 belongs to the amorphous structure of PLA, which confirms the successful addition of PLA[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eElectrochemical performance analysis\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe charge-discharge curves of PANI, P-20, P-50 and P-80 in 1M Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e electrolyte under the potential window of -0.4V to 0.6V at different current as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. It can be seen that the charge and discharge of all samples are not straight lines, which indicates the existence of pseudocapacitance behavior. The discharge time decreases with the increase of current density. The charge-discharge curves of all samples are almost the same when the current density is changed, which shows that the electrochemical properties of the materials are stable in the current density range of 0.5-5A/g. At the current density of 1A/g, the discharge time of P-50 was the longest, which indicated that the specific capacitance of PANI was increased by adding proper amount of graphene. According to the formula (2), the specific capacitance of the sample at different current densities is calculated and the ratio curve of Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea is obtained. At the current density of 0.5 A/g, the specific capacitance of P-50 is 348.1 F/g, which is 27.8% higher than that of PANI (272.4 F/g). It can be seen from the figure that the specific capacitance of P -50 is larger at different current densities, indicating that the electrochemical properties of PANI are improved by adding proper amount of graphene.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn order to investigate the electrochemical behavior of the electrode materials, the cyclic voltammetric curves of the samples were determined at a sweep rate of 0.01 v/s at a potential window of -0.4 -1.2 V, as shown by Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb. It can be found that the redox peak of PANI become more obvious with the increase of the content of graphene from 0 to 50 mg. However, when the content of graphene increases to 80 mg, the redox peak appears a significant deviation and the area also decreases. This phenomenon can be attributed to the excessive graphene cover up the good electrochemical properties of PANI. According to formula (1), it can be inferred that under the same potential window and scanning speed, the larger the area surrounded by the CV curve is, the larger the capacitance of the sample with the same quality of the active substance. In addition, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb further confirmed the pseudocapacitance property of PANI materials.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e are GCD curves and magnification diagrams of electrode materials with PLA as binder. It can be seen that the charging and discharging time of PANI and P-50 decreased with the increase of PANI content under different currents, when the mass ratio of sample, acetylene black and PLA is 8:1:1, the specific capacitance is higher. In addition, as the content of PLA increases, there is no new discharge platform appears in the GCD curve, indicating that PLA does not redox in this system and does not provide pseudo-capacitance. The sample with PLA as adhensive has obvious voltage drop, compared with that of PVDF as adhensive, in the same charge-discharge interval and current density. It is due to the addition of PLA increases the contact resistance between the electrode and the electrolyte, which leads to the decrease of the electrochemical performance of the electrode.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe cyclic voltamphere of PANI and P-50 with different PLA at 0.01 V/s is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e. It can be observed from the graph that the area enclosed by the CV curve decrease with the increase of PLA content. It indicated that the specific capacitance decrease and the reduction potential of electrode materials with different proportions does not change significantly. When 0.02g PLA was added, the redox peak intensity of PANI and P-50 decreased, which was due to the excessive PLA hindering the contact between electrode material and electrolyte, and the reduction of electrolyte ions involved in the electrochemical reaction, the portion of the electrode active material utilized is reduced, resulting in a smaller specific capacitance.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe cyclic stability of P-50\u0026thinsp;+\u0026thinsp;PLA and P-50\u0026thinsp;+\u0026thinsp;PVDF was tested with a voltage window of 0.01-0.6V in 0.5 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e solution, results as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e. Curves of a\u003csub\u003e1\u003c/sub\u003e, a\u003csub\u003e2\u003c/sub\u003e (b\u003csub\u003e1\u003c/sub\u003e, b\u003csub\u003e2\u003c/sub\u003e) were the voltage-capacity curves of P-50\u0026thinsp;+\u0026thinsp;PLA (P-50\u0026thinsp;+\u0026thinsp;PVDF) initial and after 500 cycles, respectively. As can be seen from the graph, the specific capacity of P-50\u0026thinsp;+\u0026thinsp;PLA decreased from 50 mAh/g to 36 mAh/g, and the capacitance retention rate was 71%, while the specific capacity of P-50\u0026thinsp;+\u0026thinsp;PVDF decreased from 62 mAh/g to 53 mAh/g, and the capacitance retention rate was 86%. From this, it can be seen that the electrode with PLA as binder is not as stable as that with PVDF as binder, but it still has a considerable specific capacity after 500 charge-discharge cycles.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eDegradation behavior analysis of P-50\u0026thinsp;+\u0026thinsp;PLA/P-50\u0026thinsp;+\u0026thinsp;PVDF\u003c/h2\u003e \u003cp\u003eThe P-50, acetylene black and PLA samples (P-50\u0026thinsp;+\u0026thinsp;PLA) with mass ratio of 8:1:1 and the P-50, acetylene black and PVDF samples (P-50\u0026thinsp;+\u0026thinsp;PVDF) with mass ratio of 8:1:1 were selected as control, the electrochemical properties of P-50\u0026thinsp;+\u0026thinsp;PLA during degradation were studied. Several electrode plates were prepared in the same batch and put into 1M Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e electrolyte. The GCD curves were measured at different time intervals, the specific capacitance was calculated, and the change of specific capacitance with time was recorded, the results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ea, it could be observed that the capacitance value of the sample with PVDF as binder was basically stable at 300 F/g for the first three days, with a slight increase to 326.8F/g on the fourth day, followed by a gradual decrease. The values measured at intervals of 20 and 30 days did not fluctuate much. After 90 days, the specific capacitance decreased by about 10%, indicating that the electrochemical properties of electrode materials with PVDF as binder were stable. After replacing PVDF with PLA, the specific capacitance of the electrode material decreased, and on the third day, the P-50\u0026thinsp;+\u0026thinsp;PLA's specific capacitance increased, which is due to the electrolyte immersion for a long time, so that the electrode and electrolyte fully contact, participate in the electrode reaction of active substances increased. On the fourth day, the specific capacitance of P-50\u0026thinsp;+\u0026thinsp;PLA decreased rapidly, and then decreased slowly with time. After 90 days, the specific capacitance of P-50\u0026thinsp;+\u0026thinsp;PLA decreased by 28%, indicating that PLA gradually degraded over time, which has affected the electrochemical properties of electrode materials. Figure\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003eb shows the CV curve after 90 days of placement of the electrode material. As can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003eb, P-50 still has obvious redox peak and pseudocapacitance, but the area enclosed by the CV curve is reduced, this is corresponding to the degradation of the electrode material, and the degradation behavior of the electrode with PLA as adhensive is further verified from the side.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eTo sum up, grapheme/PANI composites and PANI were successfully synthesized by in situ chemical oxidation. The SEM images show that the P-50 nanorods have higher specific surface area and higher porosity, which lead to more active materials are involved in the electrochemi cal reaction. Instead of the traditional binder PVDF, the biodegradable PLA was used, and the electrode material remained the same Faraday redox.With the increase of PLA content, the resistance between electrode material and electrolyte increases, and the specific capacitance decreases. The P-50\u0026thinsp;+\u0026thinsp;PVDF kept good stability, and the capacitance drops slightly after 90 days, while the specific capacitance of P-50\u0026thinsp;+\u0026thinsp;PLA decreased by 28% after 90 days due to the degradation of PLA. Based on the PLA of environmental protection, this paper provides a new idea for the research of environmentally friendly degradable super capacitors.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Liang. The first draft of the manuscript was written by Liang and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGoel A, Mashangva TT, Garg A et al (2023) Synthesis of NiCo2O4/rGO/PANI ternary nanocomposite for electrochemical performance and impact of doping on pure PANI. Journal of Materials Science: Materials in Electronics 34(27):http://doi.org/10.1007/s10854-023-11234-8\u003c/li\u003e\n\u003cli\u003eOkafor OB, Popoola API, Popoola OM et al (2023) Review of advances in improving thermal, mechanical and electrochemical properties of polyaniline composite for supercapacitor application. Polymer Bulletin 81(1):189-246. http://doi.org/10.1007/s00289-023-04710-y\u003c/li\u003e\n\u003cli\u003eZuo W, Li R, Zhou C et al (2017) Battery‐Supercapacitor Hybrid Devices: Recent Progress and Future Prospects. 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Desalination. 234 (1-3): 212\u0026ndash;220. http://doi.org/ 10.1016/j.desal.2007.09.088\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Graphene/polyaniline composites, Polylactic acid, Biodegradable supercapacitors, Conductive polymer","lastPublishedDoi":"10.21203/rs.3.rs-4261310/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4261310/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eConductive polymer polyaniline (PANI) is a hot research topic in pseudocapacitor electrode materials due to its advantages of low preparation cost and high specific capacitance. In this work, PANI and graphene/polyaniline composites (Gr/PANI) were prepared by in-situ chemical polymerization. Biodegradable polymer polylactic acid (PLA), as adhensive of electrode material for supercapacitor was used to replace the traditional adhensive polyvinylidene fluoride (PVDF). The morphology and structure of the materials were characterized by SEM and FTIR. Electrochemical behavior was performed by galvanostrotic charge-discharge (GCD), cyclic voltamphe (CV). Results showed PANI compounded with 50 mg graphene (P-50) exhibit excellent electrochemical behavior. The specific capacitance of P-50/PVDF (348.1 F/g at current density of 0.5 A/g) was 27.8% higher than that of undoped PANI. The specific capacitance maintance of P-50/PLA (71.1% content) was 14.4% less than that of P-50/PVDF (85.5%) after 500 number cycles. In addition, the influence of PLA degradation of 90 days on the electrochemical performance of electrode material was studied. Results showed that the specific capacitance at 1 A/g current density decreased from 232.2 F/g to 166.8 F/g after 90 days, compared with that with PVDF from 303 F/g to 274 F/g, The reduction was 18.5%, and it revealed that the PLA may be used in energy storage devices as degradable adhesive.\u003c/p\u003e","manuscriptTitle":"Preparation and Electrochemical Stabilities Study of Graphene/Polyaniline Composites with Polylactic Acid as Biodegradable Adhesive","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-17 13:00:08","doi":"10.21203/rs.3.rs-4261310/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"10540197-9b43-4b42-98bd-4a633a4d63c7","owner":[],"postedDate":"April 17th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-30T09:27:47+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-17 13:00:08","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4261310","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4261310","identity":"rs-4261310","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}