Effect of Manganese and Zinc co-dopants on electrochemical properties of vanadium oxide (V2O5) based electrode: application for supercapacitor

Effect of Manganese and Zinc co-dopants on electrochemical properties of vanadium oxide (V2O5) based electrode: application for supercapacitor | 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 Effect of Manganese and Zinc co-dopants on electrochemical properties of vanadium oxide (V 2 O 5 ) based electrode: application for supercapacitor H. Ghannam, Z. Rossi, S. Haloui, A. Elmouwahidi, A. Aouni, T. Tite, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3856870/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 Vanadium oxides have been investigated for their potential use in electrochemical supercapacitors due to their variable oxidation states yielding surface redox. However, its electrochemical performance is limited by its poor electronic and ionic conductivity. In an attempt to improve the electronic conductance and electrochemical performance of V 2 O 5 , ( Mn, Zn ) co-doped V 2 O 5 is investigated. ( Mn, Zn ) (2, 2) wt% co-doped V 2 O 5 provides the high specific capacitance, it achieves 23.72 F/g at a scan rate of 5 mV/s , and it is characterized by very low charge transfer resistance (301 mΩ ). At 2 A/g current density, its power density and energy density are about 2520 Wkg − 1 , and 4.85 Whkg − 1 respectively. Because of its good electrochemical performance, ( Mn, Zn ) (2, 2) wt% co-doped V 2 O 5 has great application prospects in supercapacitors. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1. Introduction Recent years have yielded significant challenges for the development of supercapacitors with high energy density, good electrochemical performance, and low production costs. The electrode materials and electrolytes are the main elements in supercapacitors, intimately influencing the electrochemical performance. [ 1 ] Undoubtedly, carbon materials are undergoing significant attention as ideal electrode materials in terms of cycle life and specific power, mainly due to their high electrochemical stability, good electrical conductivity, and large specific surface areas with suitable porous structures. [ 2 ] Despite these properties, the accumulation of charges occurring electrostatically on the porous carbon materials is unfortunately limited, typically in the range of 10–50 µFcm − 2 . [ 3 ] In fact, the high porous surface area of active carbon material, which is not electro-chemically active, leads to a high internal series resistance, contributing to the reduction of specific double layer capacitance. [ 2 ] Transition metal oxides ( TMOs ) ( e.g., VO X , ZnO ) have showed new promises for material electrodes. [ 4 , 5 ] In fact, they can store energy through fast and reversible faradic reactions (redox reactions) between electrochemically active metal oxide material and electrolyte ions. They are contributing to increasing the pseudo-capacitance value of a supercapacitor. It is worth mentioning that the metal oxide materials that are electrochemically active exhibit far larger pseudocapacitance values (10–100 times greater than carbon materials) and energy densities. [ 6 ] VO x is a TMO existing in various compositions ( e.g., V 2 O 5 , V 2 O 3 , and VO 2 ). It is characterized by unique physico-chemical properties, such as layered structures, thermal stability, high theoretical capacity, availability, and overall safe use. [ 5 ] As an electrode material, vanadium pentoxide ( V 2 O 5 ) has a high theoretical specific capacitance value of 2120 F/g . [ 7 ] Experimentally, the specific capacitance of V 2 O 5 is mainly related to the nature of the electrolyte used. In general, there are three electrolytes used in electrochemical supercapacitors: aqueous electrolyte, organic electrolyte, and ionic liquid. The advantages of aqueous electrolytes over organic and ionic liquids lie in their high ionic concentration, lower resistance, and high capacitance and power. [ 3 ] Different values of the specific capacitance of the V 2 O 5 electrode were found as a function of the nature of the aqueous electrolyte. [ 8 ] In an aqueous 2 M KOH electrolyte, V 2 O 5 nanofibers displayed a specific capacitance of 8 F/g . In 1 M H 2 SO 4 electrolyte, V 2 O 5 nanofibers showed a value of 106 F/g and reached a value of 190 F/g in aqueous 2 M KCl electrolyte. [ 9 ] For energy storage applications, the layered structure of V 2 O 5 allows for ion intercalation in-between V 2 O 5 layers, which results in texture and morphological changes when metal ions are added to the structure. It is worth pointing out that the Achilles heel of V 2 O 5 is related to its low conductivity, stability, and capacity loss that occurs during cycling, which is thought to be caused by problems with low conductivity and material deterioration. [ 10 , 11 ] Doping is often recommended to improve the electronic conductance of V 2 O 5 , its stability, and therefore its electrochemical performance. [ 11 ] Several doping elements were used in an attempt to improve the electrochemical performance of V 2 O 5 -based electrodes. It was reported that the amorphous V 2 O 5 has a higher electronic conductivity after being doped with Zn, Cu , and Ag . [ 12 – 15 ] Additionally, doping V 2 O 5 with Mn was observed to improve the cyclability and stability of V 2 O 5 based electrodes. [ 16 ] Also described as cathodes for rechargeable metal-ion batteries are flexible nanostructures of Fe -doped V 2 O 5 , and Cr -doped V 2 O 5 , all of which exhibit increased stability and better metal ion intercalation behavior compared to pure V 2 O 5 . [ 17 , 18 ] In the present work, we have synthesized ( Mn, Zn ) co-doped V 2 O 5 on nickel foam by spray pyrolysis. The effect of ( Mn, Zn ) equi-mass co-doping on the physico-chemical properties of V 2 O 5 has been studied. The physico-chemical properties of the thin films were multi-parametrically surveyed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Raman spectroscopy. The electrochemical performance of the samples was measured using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge methods (GCD). 2. Experimental section Material synthesis In this study, we prepared both undoped and ( Mn, Zn ) co-doped V 2 O 5 thin films using a spray pyrolysis technique. The preparation of the solutions involved dissolving 0.05M of vanadium (III) chloride, VCl 3 (Sigma, 99%), as the primary component. Additionally, manganese (II) chloride tetrahydrate, MnCl 2 •4H 2 O (Sigma - Aldrich, 99%), and zinc chloride, ZnCl 2 (Sigma - Aldrich, 98–100.5%), were used as co-dopant elements. For the undoped V 2 O 5 sample, we prepared an aqueous solution of 0.05M VCl 3 by dissolving it in 30 ml of distilled water. For the ( Mn, Zn ) co-doped V 2 O 5 samples, we introduced various weight ratios of ( Mn, Zn ) ((1,1), (2,2), and (3,3) wt%) into a 0.5M VCl 3 aqueous solution of 30 ml. Each solution was meticulously stirred and then spray-pyrolyzed at a rate of 2 ml/min onto nickel foam substrates, which were positioned on a pre-heated hot plate set at 300°C. It should be noted that undoped V 2 O 5 is referred to as "0%", and ( Mn, Zn ) co-doped V 2 O 5 samples with weight ratios of ((1,1), (2,2), and (3,3) wt%) were identified as samples 2, 4, and 6wt%, respectively. Material characterization Textural characterizations The structural properties of the co-doped thin films were investigated by Raman spectroscopy (SENT ERRAII, BRUKER). Scanning electron microscopy coupled with energy dispersive X-ray (SEM − EDX) spectroscopy (Hirox MEB SH − 4000MB) was used for the characterization of surface morphology and chemical element analysis. SEM images were investigated with an accelerated voltage of 30 KV . Electrochemical characterizations The electrochemical performance of ( Mn, Zn ) co-doped V 2 O 5 (0, 2, 4, and 6wt%) thin films was investigated using CV , GCD , and EIS . A conventional three-electrode cell was employed, consisting of a saturated calomel electrode (SCE) as the reference electrode, a platinum rod as the counter electrode, and a working electrode composed of V 2 O 5 :Mn, Zn (0, 2, 4, and 6 wt%) on a Ni foam acting as the charge collector. These electrodes were connected to the OrigaMaster software on one end and vertically immersed in an aqueous electrolyte of 1 M potassium hydroxide ( KOH ) at ambient temperature on the other end. CV measurements were conducted in the presence of faradic reactions. GCD was performed at different applied currents (50, 75, 100, and 200 mA ), and EIS was carried out under the same aqueous electrolyte conditions as CV characterization, covering a frequency range of 0.1 Hz to 20 kHz at an equilibrium potential. The specific capacitance ( C sp ) was calculated from the CV responses using the following equation: $${C}_{sp}=\frac{1}{mv \varDelta V}\int I\left(V\right)dV$$ 1 Where I is the current, m is the mass of the electroactive materials, v is the scan rate, and ∆V is the potential window. The following equations were used to compute the specific capacitance C sp , energy density E g , and power density P g from GCD results: $${C}_{SP}=\frac{It}{m\varDelta V}$$ 2 $${E}_{g}=\frac{1}{2}{C}_{SP}{(\varDelta V)}^{2}$$ 3 $${P}_{g}=\frac{{E}_{g}}{\varDelta t}$$ 4 Where, I is the charge - discharge current ( A ), ∆V is the potential range ( V ), m is the mass of the electroactive materials ( g ), and t is the discharging time ( h ). 3. Results and discussion Textural characterization Figure 1 SEM images of undoped and ( Mn, Zn ) co-doped V 2 O 5 . The SEM images of the samples show a total covering of the nickel foam by a granular thin layer of V 2 O 5 . Where ( Mn, Zn ) weight percent doping affects the density and size of the non-uniform granular structure of V 2 O 5 . (Fig. 1 ) For an undoped V 2 O 5 sample, the morphology shows a smooth aspect to the granular form, and for ( Mn, Zn ) 2wt% co-doped V 2 O 5 shows a low-hills form. While the morphology of ( Zn, Mn ), 4, and 6 wt% co-doped V 2 O 5 depicts the onset of a dense, irregular granular structure. Indeed, a number of works have reported on the impact of Zn and Mn on morphological features. [ 19 – 22 ] where the dopant elements (Zn and Mn ) were shown to enhance the formation of V 2 O 5 nanostructures. Kumar et al. [ 20 ] were reported that Zn boosted the nucleation sites for the formation of V 2 O 5 . Additionally, the buildup of V 2 O 5 nanoparticles was blamed for the increase in the surface area to volume ratio. In our case, the overgrown agglomeration of irregular granular structure in the sample c offers a maximum surface area, allowing it to be a nominated sample for maximum ion exchange at the electrode/electrolyte interface. EDX spectra show the chemical elements of undoped and ( Mn, Zn ) 4wt% co-doped V 2 O 5 samples (Fig. 2 (a)). As it is detected, Ni is the main constitutive element of the samples attributed to the nickel foam current collector. In addition, the deposit elements V and O are also shown with a molar ratio V/O very close to the nominal composition of V 2 O 5 . Indeed, undoped V 2 O 5 displayed a V/O molar ratio of 0.41 and 0.38 for ( Mn, Zn ) 4wt% co-doped V 2 O 5 . Moreover, the presence of ( Mn, Zn )-doping atoms as a function of wt% variation is depicted in SEM − EDX mapping analysis (Fig. 2 (b)). As it is shown, the Mn and Zn atoms are homogeneously dispersed on the sample surfaces and increase as a function of wt%. Furthermore, an equi-massic doping of ( Mn, Zn ) gives rise to the presence of Mn atoms a bit more than Zn ones due to their reduced atomic mass (am ( Mn ) = 54.93 u < am ( Zn ) = 65.38 u ). Figure 3 shows the Raman spectra of undoped and ( Mn, Zn ) co-doped V 2 O 5 (2, 4, and 6wt%) thin films on nickel foam. The Raman analysis for undoped sample shows peaks localized at 103, 146, 196, 283, 405, 481, 527, 705 and 996 cm − 1 . These peaks correspond to the characteristic vibration modes of the orthorhombic phase of V 2 O 5 . [ 23 ] The peak at 196 cm − 1 is attributed to the stretching mode of V O for B1g symmetry vibration. The bands held in 283, 403, and 996 cm − 1 are referenced to V = O bending vibrations related to B2g and Ag symmetry vibrations. Raman band at 527 cm − 1 is an outcome of the triply coordinated oxygen, V 3 − O , stretching modes ascribed to Ag symmetry vibration. Finally, the peak appears at 705 cm − 1 assigned to stretching and bending modes of doubly coordinated oxygen, V 2 O , related to B2g symmetry vibration. On the other hand, the incorporation of ( Mn, Zn ) modifies the peaks intensity of the Raman spectra of V 2 O 5 . It is noteworthy that characteristic peaks of the V 2 O 5 located at 196, 283, 405, 481, 527, and 705 cm − 1 decrease and almost disappear by raising the amount of ( Mn, Zn ). Moreover, the main peak located at 146 cm − 1 shifts from 142 to 138 cm − 1 when the (Mn) increases from 0 to 6wt%. This shift is probably attributed to the V 2 O 5 lattice distortion caused by the ( Mn, Zn ) dopants incorporation into the V 2 O 5 structure. Furthermore, the intensity of the main peak located at 146 cm − 1 decreases with ( Mn, Zn ) addition until 4wt% and re-increases for 6wt%. This result makes sample 4wt% a transitor between V 2 O 5 Raman signals. Electrochemical characterization The CV curves are presented in the Fig. 4 , all samples show a pseudo-capacitive behavior where a contribution of faradic current is occurring due to the redox reaction involved between the electrode/electrolyte along a cyclic sweep between 0 and 0.7 V . During the charging process from 0 to 0.7 V , a current anodic peak appears, which is the result of an oxidation reaction between V 2 O 5 electrode material and KOH aqueous electrolyte. During the discharging process from 0.7 to 0 V , a cathodic peak appears, which is the result of the reduction of oxidized elements obtained during the charging process. As a summary, the redox reaction displayed in the CV analysis is expressed as follows: Charging process, (V 2 O 5 - K + ) → (V 2 O 5 ) + K + + e − (5) Discharging process, (V 2 O 5 ) + K + + e − → (V 2 O 5 - K + ) (6) The CV curves of all samples maintain their shape for more than 100 cycles at a scan rate of 200 mV/s , demonstrating good cycling stability. A shift in the oxidation and reduction potentials was observed with the scan rate, which is indicative of the slow electrochemical system’s telltale indicator. For slow electrochemical systems, the oxidation/reduction potential depends on the scan rate. In order to describe the kinetics of electrochemical reactions, the charge transfer coefficient is calculated using the Butler-Volmer equation. [ 24 ] The following Butler-Volmer equation is used to define the anodic transfer coefficient: $${E}_{ox}=Cst+\frac{RT}{{\beta }_{ox}nF}ln\surd v$$ 7 With, F is the Faraday constant in C/mol, n is the number of electrons involved in the electrode reaction, v is scan rate in V/s , R is universal gas constant in J/Kmol , β is charges transfer coefficient (dimensionless number), and T is absolute temperature in K . The anodic charge coefficient refers to the transfer of electrons from the electrolyte to the anode, which involves the desertion of electroactive species from the surface of the electrode. It was reported that the charge transfer coefficient for the transfer of one electron is close to 0.5, which fits our case [ 24 ]. Indeed, the charge transfer coefficient is about 0.42 for undoped V 2 O 5 and 0.34 for ( Mn, Zn ) co-doped V 2 O 5 . As a result, the ( Mn, Zn ) co-doped V 2 O 5 electrodes have a charge transfer coefficient inferior to the undoped one, which indicates that the co-doping has improved the charge transfer process. The diffusion of K + ions to the electrode’s V 2 O 5 surface restricts the amount of current that can travel through the electrode. The concentration gradient close to the electrode affects the diffusion flux. The concentration gradient is then influenced by the rate of solution diffusion. The concentration of the species at the electrode surface also changes when the cell voltage does. A higher current result from a faster voltage sweeps because a higher concentration gradient is created close to the electrode. The impact of scan rate on the peak current for a CV experiment is described by the Randles-Evk equation. [ 25 ] The diffusion coefficient of the electroactive species can be calculated using the relationships established by this equation. Evidence for a chemical redox process between the electrode and the electrolyte can be found in linear graphs of I vs. v 1/2 . (Fig. 6 ) $$I=2.69.{10}^{5}\times {n}^{\frac{3}{2}}\times S\times C\times {D}^{\frac{1}{2}}\times {v}^{\frac{1}{2}}\times {\beta }^{\frac{1}{2}}$$ 8 Where S is the electrode area in cm 2 , F is the Faraday constant in C/mol , D is the diffusion coefficient in cm 2 /s , and I is the maximum current in amps. n is typically the number of electrons transferred in the redox event. C stands for concentration in moles/cm 3 , v for scan speed in V/s , R for gas constant in J/Kmol , β for charge transfer coefficient, and T for temperature in K . The constant has units of Cmol − 1 V 1/2 and a value of 2.69.10 5 . The diffusion coefficient of the electroactive species can be calculated using the relationships established by the Eq. ( 8 ). According to Eq. ( 8 ), the K + diffusion coefficients for the charge process were calculated to be 1.17.10 − 3 , 1.95.10 − 3 , 3.6.10 − 3 , and 2.88.10 − 3 cm 2 /s for undoped, 2, 4, 6% respectively. The ionic diffusion in the bulk material would be optimized by the co-doped 4% material’s appropriately large surface area. Thus, it is reasonable to conclude that a larger surface area and a higher D (K + ) value may account for the improved rate performance since they would facilitate a quicker potassium ion transfer procedure. The specific capacitance of the undoped and ( Mn, Zn ) co-doped electrode is depicted in Fig. 7 as a function of the voltage scan rate (Eq. ( 1 ). The results show that ( Mn, Zn ) co-dopants improve the specific capacitance of electrodes based on V 2 O 5 . ( Mn, Zn ) 4% co-doped V 2 O 5 displays a higher specific capacitance of ≈ 23.72 F/g at 5 mV /s , which is about 30% higher than the value found for undoped V 2 O 5 ( C sp ≈ 13 F/g ). Since the ion movement is restricted to the electrode material’s surfaces under these circumstances, the specific capacitance remained almost constant for higher scan rates (> 50 mV/s ). In this case, the EDLC dominates the other mechanisms. At lower scan speeds (< 50 mV/s) , the majority of the active surface is utilized by the ions for charge storage, leading to a larger specific capacitance. The reversibility of the reaction that occurs during the charge and discharge processes is defined by coulombic efficiency ( CE ). It is the ratio between the charges generated during the charging and discharging processes. $$CE=\frac{{Q}^{-}}{{Q}^{+}}.100$$ 9 Table 1 Coulombic efficiency of undoped and co-doped V 2 O 5 samples at different scan rates. Samples CE (0%) CE (2%) CE (4%) CE (6%) 5mV/s 89 86 85 85 10mV/s 96 89 90 90 50mV/s 96 94 92 92 100mV/s 98 96 92 92 150mV/s 96 96 94 100 200mV/s 95 100 95 95 The CE is approaching 100% for all samples and for various scan rates, which indicates the absence of irreversible modification of the electrode and also the absence of electrolyte decomposition at the V 2 O 5 surface. (Table 1 ) The GCD tests carried out in the voltage window of 0.0 to 0.7 V at various current density between 2 and 8 A/g are shown in Fig. 8 . The CV curves and the non-linearity between potential and time suggest that the examined materials’ capacitance is not constant over the potential ranges during both charge and discharge cycles. The GCD curves display a pseudocapacitive behavior of the electrode originating from the electrochemical redox reaction on the electrode/electrolyte interface. Table 2 Specific capacity, energy density, and power density of undoped and co-doped V 2 O 5 at a current density of 2 A/g . 2 A/g t dischage (s) C sp (F/g) E g (Wh/kg) P g (Wkg − 1 ) 0% 2.92 8.34 2.04 2520 2% 3.74 10.68 2.62 2520 4% 6.94 19.82 4.85 2520 6% 4.69 13.4 3.28 2520 The results show an improvement of the electrochemical properties with the doping in terms of specific capacity and energy density (Fig. 9 ), (Table 2 ). The best performance was obtained for 4wt% co-doped V 2 O 5 , achieving a specific capacitance of 19.82 F/g , power density and energy density of 2520 Wkg − 1 , and 4.85 Whkg − 1 respectively at 2 A/g . Figure 10 dipects Nyquist plots for undoped and ( Mn, Zn ) co-doped V 2 O 5 electrodes at open circuit potential. In the higher frequency range, a muted semicircle is present, preceded by an ascending line in the lower frequency region, where their behaviors are primarily capacitive. The depressed semicircles often signify minor resistances to charge exchange between electrode and electrolyte. The diameter of the semicircle represents the kinetic resistance to the ion transfer, known as charge transfer resistance of the redox reactions. At the low-frequency region, the inclined line is related to solid-state diffusion of positive ions in the electrode materials. [ 26 ] Experimental impedance results are analyzed by curve fitting (using OrigaMaster software) to an appropriate electrical equivalent circuit. The Randles circuit of electrode consists of the electrolyte resistance R1 in series with the parallel combination of the double-layer capacitance C2 and impedance Fig. 10 EIS of undoped and ( Mn, Zn ) co-doped V 2 O 5 accompanied by their corresponding equivalent circuit. W1 and charge transfer resistance R2 , as indicated in the inset of Fig. 10 . Moreover, for all samples, W1 represents the Warburg impedance evidencing by the 45-degree line which indicates the diffusion of K + though a semi-infinite medium. The R2 is rather low for ( Mn, Zn ) co-doped 4wt% V 2 O 5 , 301 mΩ , which is attributed to the improved ionic conduction and electrolyte diffusion through the surface asperities of the electrode material. 4. Conclusions In this work, undoped and (Mn, Zn) co-doped V 2 O 5 thin films were synthesized on nickel foam by spray pyrolysis. V 2 O 5 phase was confirmed by Raman spectroscopy. It was found that the co-doping induced a Raman shift and broadening of the peaks. The morphological analysis indicated good uniformity of the coating for all the samples, with an overgrown agglomeration of irregular granular structure observed for the co-doping 4wt% sample. Furthermore, EDX mappings confirm the presence of Zn and Mn dopants in a higher proportion by increasing the concentration. Regarding electrochemical analysis, an improvement of the electrochemical properties with doping in terms of specific current, specific capacity, and charge electron transfer. The best performance was obtained for 4wt% co-doped V 2 O 5, achieving 23.72 F/g at scan rate of 5 mV/s , power density and energy density of 2520 Wkg − 1 , and 4.85 Whkg − 1 respectively at 2 A/g . Declarations Conflicts of interest There are no conflicts to declare. Acknowledgements The authors thank “Agence universitaire de la Francophonie (AUF)” for the Eugen Ionescu research scholarship (H. GHANNAM). The electrode elaboration and characterization were performed at the Materials, Systems and Energy Engineering Laboratory (MaSEEL), ERCMN, (UAE/U01FST). Author Contribution H. Ghannam: conceptualization, formal analysis, methodology, data curation, writing – original draft, visualization, project administration.Z. Rossi: formal analysis, investigation, visualization, writing – review & editing.S. Haloui formal analysis, investigation, visualization.A. Aouni: investigation, resources, data curation, formal analysis, writing – review & editing, visualization.A. Elmouwahidi: investigation, visualization, writing – review & editing.T. Tite: formal analysis, investigation, visualization, writing – review & editing.M. Diani: investigation, resources, data curation, formal analysis, writing – review & editing, visualization.A. Chahboun: investigation, resources, writing – review & editing, visualization, supervision, project administration. References Poonam, K. Sharma, A. Arora and S. Tripathi, Journal of Energy Storage, 2019, 21, 801–825. Y. Zhang, H. Feng, X. Wu, L. Wang, A. Zhang, T. Xia, H. Dong, X. Li and L. Zhang, International Journal of Hydrogen Energy, 2009, 34, 4889–4899. G. Wang, L. Zhang and J. Zhang, Chem. Soc. Rev., 2012, 41, 797–828. H. Ghannam, J. P. B. Silva and A. Chahboun, RSC Adv., 2021, 11, 23346–23354. H. Qin, S. Liang, L. Chen, Y. Li, Z. Luo and S. 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Impact of Zn2+ Doping on the Structural, Morphological and Photodiode Properties of V2O5 Nanorods. J Inorg Organomet Polym 31, 1066–1078 (2021). https://doi.org/10.1007/s10904-020-01751-y S. K. Rai, R. Rai, R. Bairy, M. Murari, A. Jayarama and R. Pinto, Materials Today: Proceedings, 2021, 35, 469–473. H. Zeng, D. Liu, Y. Zhang, K. A. See, Y.-S. Jun, G. Wu, J. A. Gerbec, X. Ji and G. D. Stucky, Chemistry of Materials, 2015, 27, 7331–7336. F. Urena-Begara, A. Crunteanu and J.-P. Raskin, Applied Surface Science, 2017, 403, 717–727. R. Guidelli, R. G. Compton, J. M. Feliu, E. Gileadi, J. Lipkowski, W. Schmickler and S. Trasatti, Pure and Applied Chemistry, 2014, 86, 245–258. A. Sevcík, Collection of Czechoslovak Chemical Communications, 1948, 13, 349–377. https://doi.org/10.1135/cccc19480349 W. Gomes and D. Vanmaekelbergh, Electrochimica Acta, 1996, 41, 967–973. Additional Declarations No competing interests reported. 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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-3856870","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":266855942,"identity":"e6eee135-cb9f-4ea5-bc57-a9ddef9dfbf2","order_by":0,"name":"H. 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Rossi","email":"","orcid":"","institution":"Abdelmalek Essaadi University, ERCMN, (UAE/U01FST)","correspondingAuthor":false,"prefix":"","firstName":"Z.","middleName":"","lastName":"Rossi","suffix":""},{"id":266855944,"identity":"f6623ca4-6357-4538-9344-c08b03bd481f","order_by":2,"name":"S. Haloui","email":"","orcid":"","institution":"Abdelmalek Essaadi University, ERCMN, (UAE/U01FST)","correspondingAuthor":false,"prefix":"","firstName":"S.","middleName":"","lastName":"Haloui","suffix":""},{"id":266855945,"identity":"6868f49c-3128-4b99-ab1e-28e0b5257d38","order_by":3,"name":"A. Elmouwahidi","email":"","orcid":"","institution":"Materiales Polifuncionales Basados en Carbono (UGR-Carbon), Universidad de Granada","correspondingAuthor":false,"prefix":"","firstName":"A.","middleName":"","lastName":"Elmouwahidi","suffix":""},{"id":266855946,"identity":"35323c1d-3063-438a-9182-e7c6538a5805","order_by":4,"name":"A. Aouni","email":"","orcid":"","institution":"Abdelmalek Essaadi University, ERCMN, (UAE/U01FST)","correspondingAuthor":false,"prefix":"","firstName":"A.","middleName":"","lastName":"Aouni","suffix":""},{"id":266855947,"identity":"84729096-8350-47e6-b75d-5f3b34a9687f","order_by":5,"name":"T. Tite","email":"","orcid":"","institution":"National Institute of Materials Physics","correspondingAuthor":false,"prefix":"","firstName":"T.","middleName":"","lastName":"Tite","suffix":""},{"id":266855948,"identity":"91ad752c-780e-4407-a1b9-293ab8411f44","order_by":6,"name":"M. Diani","email":"","orcid":"","institution":"Abdelmalek Essaadi University, ERCMN, (UAE/U01FST)","correspondingAuthor":false,"prefix":"","firstName":"M.","middleName":"","lastName":"Diani","suffix":""},{"id":266855949,"identity":"29a8ad5a-a560-43f3-bd11-20e3d223bca7","order_by":7,"name":"A. Chahboun","email":"","orcid":"","institution":"Abdelmalek Essaadi University, ERCMN, (UAE/U01FST)","correspondingAuthor":false,"prefix":"","firstName":"A.","middleName":"","lastName":"Chahboun","suffix":""}],"badges":[],"createdAt":"2024-01-12 12:14:47","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3856870/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3856870/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":49646846,"identity":"b55779cb-22d9-483f-a722-28953a4f8e32","added_by":"auto","created_at":"2024-01-15 21:13:04","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":317194,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/d1596e701dc416d1589f9d48.png"},{"id":49646964,"identity":"4f73f465-3c15-49fd-ac4e-b9015557ee21","added_by":"auto","created_at":"2024-01-15 21:21:04","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":348771,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Energy dispersive X-ray analysis of undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) 4wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. (b) Mapping analysis of (\u003cem\u003eMn, Zn\u003c/em\u003e) doping element of (\u003cem\u003eMn, Zn\u003c/em\u003e) 2, 4, and 6wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e samples.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/c930235f0f57a9ae1c6bb43f.png"},{"id":49646615,"identity":"9cf22f01-22f7-4d09-8ca4-81a9888d3e87","added_by":"auto","created_at":"2024-01-15 21:05:04","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":192681,"visible":true,"origin":"","legend":"\u003cp\u003eRaman spectroscopy of undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) 2, 4, and 6wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e samples.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/32ec960e88df6dd956204d77.png"},{"id":49646608,"identity":"00b79440-f1b5-4d29-a3a8-41954914e921","added_by":"auto","created_at":"2024-01-15 21:05:04","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":127077,"visible":true,"origin":"","legend":"\u003cp\u003eCyclic voltammograms of nickel foam, undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) 2, 4, 6 wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e samples (the inset shows the CV curves for the 1\u003csup\u003est\u003c/sup\u003e\u003csup\u003e\u003csub\u003e \u003c/sub\u003e\u003c/sup\u003eand 100\u003csup\u003eth\u003c/sup\u003e cycle).\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/de92d319f6973a2bbed36388.png"},{"id":49646606,"identity":"ab102625-4ca5-4495-8aaf-214e54a07ad5","added_by":"auto","created_at":"2024-01-15 21:05:03","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":29515,"visible":true,"origin":"","legend":"\u003cp\u003ePlots of \u003cem\u003eE\u003c/em\u003e\u003csub\u003e\u003cem\u003eox\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e vs. ln (v\u003c/em\u003e\u003csup\u003e\u003cem\u003e1/2\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e)\u003c/em\u003e for undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) 2, 4, 6wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e samples\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/8fe76fbb8cb75e234f96484d.png"},{"id":49646607,"identity":"be494361-2444-41e2-b35c-c0495464d7a5","added_by":"auto","created_at":"2024-01-15 21:05:03","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":24429,"visible":true,"origin":"","legend":"\u003cp\u003ePlots of \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003eox\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e vs. v\u003c/em\u003e\u003csup\u003e\u003cem\u003e1/2\u003c/em\u003e\u003c/sup\u003e for undoped and (Mn, Zn) 2, 4, 6wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e samples.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/fc61dd022da1393b7d9019df.png"},{"id":49646611,"identity":"ef5d4062-5760-4bbf-80cc-73b461599eef","added_by":"auto","created_at":"2024-01-15 21:05:04","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":15178,"visible":true,"origin":"","legend":"\u003cp\u003ePlot of scan rate versus specific capacitance for undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) 2, 4, and 6wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e \u003c/em\u003esamples.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/4041b8690f952b9dbceeda60.png"},{"id":49646610,"identity":"e4d308ac-677e-483e-b44e-30512d885a08","added_by":"auto","created_at":"2024-01-15 21:05:04","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":27957,"visible":true,"origin":"","legend":"\u003cp\u003eGalvanostatic charge/discharge curves of undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) 2, 4, and 6wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e for different applied currents density.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/4a45a812bdb5808469d089c6.png"},{"id":49646848,"identity":"6760dcc5-7979-4138-8538-afafcf580cb5","added_by":"auto","created_at":"2024-01-15 21:13:04","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":16165,"visible":true,"origin":"","legend":"\u003cp\u003eGalvanostatic discharge curves of undoped and co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e \u003c/em\u003esamples at 2\u003cem\u003eA/g\u003c/em\u003e current density.\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/f2510832e08a92c057dc628e.png"},{"id":49646614,"identity":"2ab0add6-0d23-4f20-a94a-1490dafb55d2","added_by":"auto","created_at":"2024-01-15 21:05:04","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":51018,"visible":true,"origin":"","legend":"\u003cp\u003eEIS of undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e accompanied by their corresponding equivalent circuit.\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/3f8590f2044f0a941ee379f5.png"},{"id":54216440,"identity":"f6d1bc2a-18ce-4eeb-9580-b1bf26667e90","added_by":"auto","created_at":"2024-04-06 15:07:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1407674,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3856870/v1/dab0ffc8-50c4-4774-90a6-55e89217b3a1.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eEffect of Manganese and Zinc co-dopants on electrochemical properties of vanadium oxide (V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e) based electrode: application for supercapacitor\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eRecent years have yielded significant challenges for the development of supercapacitors with high energy density, good electrochemical performance, and low production costs. The electrode materials and electrolytes are the main elements in supercapacitors, intimately influencing the electrochemical performance. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] Undoubtedly, carbon materials are undergoing significant attention as ideal electrode materials in terms of cycle life and specific power, mainly due to their high electrochemical stability, good electrical conductivity, and large specific surface areas with suitable porous structures. [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Despite these properties, the accumulation of charges occurring electrostatically on the porous carbon materials is unfortunately limited, typically in the range of 10\u0026ndash;50\u003cem\u003e\u0026micro;Fcm\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;2\u003c/em\u003e\u003c/sup\u003e. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] In fact, the high porous surface area of active carbon material, which is not electro-chemically active, leads to a high internal series resistance, contributing to the reduction of specific double layer capacitance. [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Transition metal oxides (\u003cem\u003eTMOs\u003c/em\u003e) (\u003cem\u003ee.g., VO\u003c/em\u003e\u003csub\u003e\u003cem\u003eX\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eZnO\u003c/em\u003e) have showed new promises for material electrodes. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] In fact, they can store energy through fast and reversible faradic reactions (redox reactions) between electrochemically active metal oxide material and electrolyte ions. They are contributing to increasing the pseudo-capacitance value of a supercapacitor. It is worth mentioning that the metal oxide materials that are electrochemically active exhibit far larger pseudocapacitance values (10\u0026ndash;100 times greater than carbon materials) and energy densities. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/p\u003e \u003cp\u003e \u003cem\u003eVO\u003c/em\u003e \u003csub\u003e \u003cem\u003ex\u003c/em\u003e \u003c/sub\u003e is a TMO existing in various compositions (\u003cem\u003ee.g., V\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eVO\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e). It is characterized by unique physico-chemical properties, such as layered structures, thermal stability, high theoretical capacity, availability, and overall safe use. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] As an electrode material, vanadium pentoxide (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e) has a high theoretical specific capacitance value of 2120\u003cem\u003eF/g\u003c/em\u003e. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] Experimentally, the specific capacitance of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e is mainly related to the nature of the electrolyte used. In general, there are three electrolytes used in electrochemical supercapacitors: aqueous electrolyte, organic electrolyte, and ionic liquid. The advantages of aqueous electrolytes over organic and ionic liquids lie in their high ionic concentration, lower resistance, and high capacitance and power. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] Different values of the specific capacitance of the \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e electrode were found as a function of the nature of the aqueous electrolyte. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] In an aqueous 2\u003cem\u003eM KOH\u003c/em\u003e electrolyte, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e5\u003c/sub\u003e nanofibers displayed a specific capacitance of 8\u003cem\u003eF/g\u003c/em\u003e. In 1\u003cem\u003eM H\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eSO\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e electrolyte, V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e nanofibers showed a value of 106\u003cem\u003eF/g\u003c/em\u003e and reached a value of 190\u003cem\u003eF/g\u003c/em\u003e in aqueous 2\u003cem\u003eM KCl\u003c/em\u003e electrolyte. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] For energy storage applications, the layered structure of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e allows for ion intercalation in-between \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e layers, which results in texture and morphological changes when metal ions are added to the structure. It is worth pointing out that the Achilles heel of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e is related to its low conductivity, stability, and capacity loss that occurs during cycling, which is thought to be caused by problems with low conductivity and material deterioration. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] Doping is often recommended to improve the electronic conductance of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e, its stability, and therefore its electrochemical performance. [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] Several doping elements were used in an attempt to improve the electrochemical performance of V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e-based electrodes. It was reported that the amorphous \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e has a higher electronic conductivity after being doped with \u003cem\u003eZn, Cu\u003c/em\u003e, and \u003cem\u003eAg\u003c/em\u003e. [\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] Additionally, doping \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e with \u003cem\u003eMn\u003c/em\u003e was observed to improve the cyclability and stability of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e based electrodes. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] Also described as cathodes for rechargeable metal-ion batteries are flexible nanostructures of \u003cem\u003eFe\u003c/em\u003e-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eCr\u003c/em\u003e-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e, all of which exhibit increased stability and better metal ion intercalation behavior compared to pure \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn the present work, we have synthesized (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e on nickel foam by spray pyrolysis. The effect of (\u003cem\u003eMn, Zn\u003c/em\u003e) equi-mass co-doping on the physico-chemical properties of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e has been studied. The physico-chemical properties of the thin films were multi-parametrically surveyed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Raman spectroscopy. The electrochemical performance of the samples was measured using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge methods (GCD).\u003c/p\u003e"},{"header":"2. Experimental section","content":" \u003cp\u003e \u003cb\u003eMaterial synthesis\u003c/b\u003e \u003c/p\u003e \u003cp\u003eIn this study, we prepared both undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e thin films using a spray pyrolysis technique. The preparation of the solutions involved dissolving 0.05M of vanadium (III) chloride, \u003cem\u003eVCl\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e (Sigma, 99%), as the primary component. Additionally, manganese (II) chloride tetrahydrate, \u003cem\u003eMnCl\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u0026bull;4H\u003csub\u003e2\u003c/sub\u003eO (Sigma - Aldrich, 99%), and zinc chloride, \u003cem\u003eZnCl\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e (Sigma - Aldrich, 98\u0026ndash;100.5%), were used as co-dopant elements. For the undoped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e sample, we prepared an aqueous solution of 0.05M \u003cem\u003eVCl\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e by dissolving it in 30 ml of distilled water. For the (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e samples, we introduced various weight ratios of (\u003cem\u003eMn, Zn\u003c/em\u003e) ((1,1), (2,2), and (3,3) wt%) into a 0.5M \u003cem\u003eVCl\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e aqueous solution of 30 ml. Each solution was meticulously stirred and then spray-pyrolyzed at a rate of 2 ml/min onto nickel foam substrates, which were positioned on a pre-heated hot plate set at 300\u0026deg;C. It should be noted that undoped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e is referred to as \"0%\", and (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e samples with weight ratios of ((1,1), (2,2), and (3,3) wt%) were identified as samples 2, 4, and 6wt%, respectively.\u003c/p\u003e \u003cp\u003e \u003cb\u003eMaterial characterization\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eTextural characterizations\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe structural properties of the co-doped thin films were investigated by Raman spectroscopy (SENT ERRAII, BRUKER). Scanning electron microscopy coupled with energy dispersive X-ray (SEM\u0026thinsp;\u0026minus;\u0026thinsp;EDX) spectroscopy (Hirox MEB SH\u0026thinsp;\u0026minus;\u0026thinsp;4000MB) was used for the characterization of surface morphology and chemical element analysis. SEM images were investigated with an accelerated voltage of 30\u003cem\u003eKV\u003c/em\u003e.\u003c/p\u003e \u003cp\u003e \u003cb\u003eElectrochemical characterizations\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe electrochemical performance of (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e (0, 2, 4, and 6wt%) thin films was investigated using \u003cem\u003eCV\u003c/em\u003e, \u003cem\u003eGCD\u003c/em\u003e, and \u003cem\u003eEIS\u003c/em\u003e. A conventional three-electrode cell was employed, consisting of a saturated calomel electrode (SCE) as the reference electrode, a platinum rod as the counter electrode, and a working electrode composed of V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e:Mn, Zn (0, 2, 4, and 6 wt%) on a Ni foam acting as the charge collector. These electrodes were connected to the OrigaMaster software on one end and vertically immersed in an aqueous electrolyte of \u003cem\u003e1 M\u003c/em\u003e potassium hydroxide (\u003cem\u003eKOH\u003c/em\u003e) at ambient temperature on the other end. \u003cem\u003eCV\u003c/em\u003e measurements were conducted in the presence of faradic reactions. \u003cem\u003eGCD\u003c/em\u003e was performed at different applied currents (50, 75, 100, and 200 \u003cem\u003emA\u003c/em\u003e), and EIS was carried out under the same aqueous electrolyte conditions as CV characterization, covering a frequency range of 0.1 \u003cem\u003eHz\u003c/em\u003e to 20 \u003cem\u003ekHz\u003c/em\u003e at an equilibrium potential.\u003c/p\u003e \u003cp\u003eThe specific capacitance (\u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003esp\u003c/em\u003e\u003c/sub\u003e) was calculated from the \u003cem\u003eCV\u003c/em\u003e responses using the following equation:\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$${C}_{sp}=\\frac{1}{mv \\varDelta V}\\int I\\left(V\\right)dV$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere \u003cem\u003eI\u003c/em\u003e is the current, \u003cem\u003em\u003c/em\u003e is the mass of the electroactive materials, \u003cem\u003ev\u003c/em\u003e is the scan rate, and \u003cem\u003e∆V\u003c/em\u003e is the potential window.\u003c/p\u003e \u003cp\u003eThe following equations were used to compute the specific capacitance \u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003esp\u003c/em\u003e\u003c/sub\u003e, energy density \u003cem\u003eE\u003c/em\u003e\u003csub\u003e\u003cem\u003eg\u003c/em\u003e\u003c/sub\u003e, and power density \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003eg\u003c/em\u003e\u003c/sub\u003e from \u003cem\u003eGCD\u003c/em\u003e results:\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$${C}_{SP}=\\frac{It}{m\\varDelta V}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$${E}_{g}=\\frac{1}{2}{C}_{SP}{(\\varDelta V)}^{2}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ4\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$${P}_{g}=\\frac{{E}_{g}}{\\varDelta t}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e4\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere, \u003cem\u003eI\u003c/em\u003e is the charge - discharge current (\u003cem\u003eA\u003c/em\u003e), \u003cem\u003e∆V\u003c/em\u003e is the potential range (\u003cem\u003eV\u003c/em\u003e), m is the mass of the electroactive materials (\u003cem\u003eg\u003c/em\u003e), and t is the discharging time (\u003cem\u003eh\u003c/em\u003e).\u003c/p\u003e"},{"header":"3. Results and discussion","content":"\u003cp\u003e\u003cstrong\u003eTextural characterization\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e SEM images of undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. The SEM images of the samples show a total covering of the nickel foam by a granular thin layer of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. Where (\u003cem\u003eMn, Zn\u003c/em\u003e) weight percent doping affects the density and size of the non-uniform granular structure of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e) For an undoped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e sample, the morphology shows a smooth aspect to the granular form, and for (\u003cem\u003eMn, Zn\u003c/em\u003e) 2wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e shows a low-hills form. While the morphology of (\u003cem\u003eZn, Mn\u003c/em\u003e), 4, and 6 wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e depicts the onset of a dense, irregular granular structure. Indeed, a number of works have reported on the impact of \u003cem\u003eZn\u003c/em\u003e and \u003cem\u003eMn\u003c/em\u003e on morphological features. [\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e] where the dopant elements (Zn and \u003cem\u003eMn\u003c/em\u003e) were shown to enhance the formation of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e nanostructures. Kumar et al. [\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e] were reported that \u003cem\u003eZn\u003c/em\u003e boosted the nucleation sites for the formation of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. Additionally, the buildup of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e nanoparticles was blamed for the increase in the surface area to volume ratio. In our case, the overgrown agglomeration of irregular granular structure in the sample c offers a maximum surface area, allowing it to be a nominated sample for maximum ion exchange at the electrode/electrolyte interface.\u003c/p\u003e\n\u003cp\u003eEDX spectra show the chemical elements of undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) 4wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e samples (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e(a)). As it is detected, \u003cem\u003eNi\u003c/em\u003e is the main constitutive element of the samples attributed to the nickel foam current collector. In addition, the deposit elements \u003cem\u003eV\u003c/em\u003e and \u003cem\u003eO\u003c/em\u003e are also shown with a molar ratio \u003cem\u003eV/O\u003c/em\u003e very close to the nominal composition of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. Indeed, undoped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e displayed a \u003cem\u003eV/O\u003c/em\u003e molar ratio of 0.41 and 0.38 for (\u003cem\u003eMn, Zn\u003c/em\u003e) 4wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. Moreover, the presence of (\u003cem\u003eMn, Zn\u003c/em\u003e)-doping atoms as a function of wt% variation is depicted in SEM\u0026thinsp;\u0026minus;\u0026thinsp;EDX mapping analysis (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e(b)). As it is shown, the \u003cem\u003eMn\u003c/em\u003e and \u003cem\u003eZn\u003c/em\u003e atoms are homogeneously dispersed on the sample surfaces and increase as a function of wt%. Furthermore, an equi-massic doping of (\u003cem\u003eMn, Zn\u003c/em\u003e) gives rise to the presence of Mn atoms a bit more than \u003cem\u003eZn\u003c/em\u003e ones due to their reduced atomic mass (am (\u003cem\u003eMn\u003c/em\u003e)\u0026thinsp;=\u0026thinsp;54.93\u003cem\u003eu\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;am (\u003cem\u003eZn\u003c/em\u003e)\u0026thinsp;=\u0026thinsp;65.38\u003cem\u003eu\u003c/em\u003e).\u003c/p\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e shows the Raman spectra of undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e (2, 4, and 6wt%) thin films on nickel foam. The Raman analysis for undoped sample shows peaks localized at\u0026nbsp;103, 146, 196, 283, 405, 481, 527, 705 and 996\u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e. These peaks correspond to the characteristic vibration modes of the orthorhombic phase of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. [\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e] The peak at 196\u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e is attributed to the stretching mode of \u003cem\u003eV O\u003c/em\u003e for B1g symmetry vibration. The bands held in 283, 403, and 996\u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e are referenced to \u003cem\u003eV\u0026thinsp;=\u0026thinsp;O\u003c/em\u003e bending vibrations related to B2g and Ag symmetry vibrations. Raman band at 527\u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e is an outcome of the triply coordinated oxygen, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;\u003cem\u003e\u0026minus;\u0026thinsp;O\u003c/em\u003e, stretching modes ascribed to Ag symmetry vibration. Finally, the peak appears at 705\u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e assigned to stretching and bending modes of doubly coordinated oxygen, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e, related to B2g symmetry vibration. On the other hand, the incorporation of (\u003cem\u003eMn, Zn\u003c/em\u003e) modifies the peaks intensity of the Raman spectra of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. It is noteworthy that characteristic peaks of the \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e located at 196, 283, 405, 481, 527, and 705 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e decrease and almost disappear by raising the amount of (\u003cem\u003eMn, Zn\u003c/em\u003e). Moreover, the main peak located at 146\u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e shifts from 142 to 138\u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e when the (Mn) increases from 0 to 6wt%. This shift is probably attributed to the V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e lattice distortion caused by the (\u003cem\u003eMn, Zn\u003c/em\u003e) dopants incorporation into the \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e structure. Furthermore, the intensity of the main peak located at 146\u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e decreases with (\u003cem\u003eMn, Zn\u003c/em\u003e) addition until 4wt% and re-increases for 6wt%. This result makes sample 4wt% a transitor between \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e Raman signals.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eElectrochemical characterization\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe \u003cem\u003eCV\u003c/em\u003e curves are presented in the Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e, all samples show a pseudo-capacitive behavior where a contribution of faradic current is occurring due to the redox reaction involved between the electrode/electrolyte along a cyclic sweep between 0 and 0.7\u003cem\u003eV\u003c/em\u003e. During the charging process from 0 to 0.7\u003cem\u003eV\u003c/em\u003e, a current anodic peak appears, which is the result of an oxidation reaction between \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e electrode material and \u003cem\u003eKOH\u003c/em\u003e aqueous electrolyte. During the discharging process from 0.7 to 0\u003cem\u003eV\u003c/em\u003e, a cathodic peak appears, which is the result of the reduction of oxidized elements obtained during the charging process. As a summary, the redox reaction displayed in the CV analysis is expressed as follows:\u003c/p\u003e\n\u003cp\u003eCharging process,\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e(V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003eK\u003csup\u003e+\u003c/sup\u003e) \u0026rarr; (V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e) + K\u003csup\u003e+ \u003c/sup\u003e+ e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/em\u003e\u0026nbsp; \u0026nbsp;(5)\u003c/p\u003e\n\u003cp\u003eDischarging process,\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e(V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e) + K\u003csup\u003e+\u003c/sup\u003e + e\u003csup\u003e\u0026minus;\u003c/sup\u003e \u0026rarr; (V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e\u003csup\u003e- \u003c/sup\u003eK\u003csup\u003e+\u003c/sup\u003e)\u003c/em\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;(6)\u003c/p\u003e\n\u003cp\u003eThe CV curves of all samples maintain their shape for more than 100 cycles at a scan rate of 200\u003cem\u003emV/s\u003c/em\u003e, demonstrating good cycling stability. A shift in the oxidation and reduction potentials was observed with the scan rate, which is indicative of the slow electrochemical system\u0026rsquo;s telltale indicator.\u003c/p\u003e\n\u003cp\u003eFor slow electrochemical systems, the oxidation/reduction potential depends on the scan rate. In order to describe the kinetics of electrochemical reactions, the charge transfer coefficient is calculated using the Butler-Volmer equation. [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e] The following Butler-Volmer equation is used to define the anodic transfer coefficient:\u003c/p\u003e\n\u003cdiv id=\"Equ5\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equ5\" class=\"mathdisplay\"\u003e$${E}_{ox}=Cst+\\frac{RT}{{\\beta }_{ox}nF}ln\\surd v$$\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003e7\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eWith, \u003cem\u003eF\u003c/em\u003e is the Faraday constant in \u003cem\u003eC/mol, n\u003c/em\u003e is the number of electrons involved in the electrode reaction, \u003cem\u003ev\u003c/em\u003e is scan rate in \u003cem\u003eV/s\u003c/em\u003e, \u003cem\u003eR\u003c/em\u003e is universal gas constant in \u003cem\u003eJ/Kmol\u003c/em\u003e, \u003cem\u003e\u0026beta;\u003c/em\u003e is charges transfer coefficient (dimensionless number), and \u003cem\u003eT\u003c/em\u003e is absolute temperature in \u003cem\u003eK\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003eThe anodic charge coefficient refers to the transfer of electrons from the electrolyte to the anode, which involves the desertion of electroactive species from the surface of the electrode. It was reported that the charge transfer coefficient for the transfer of one electron is close to 0.5, which fits our case [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e]. Indeed, the charge transfer coefficient is about 0.42 for undoped V\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e and 0.34 for (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. As a result, the (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e electrodes have a charge transfer coefficient inferior to the undoped one, which indicates that the co-doping has improved the charge transfer process.\u003c/p\u003e\n\u003cp\u003eThe diffusion of \u003cem\u003eK\u003c/em\u003e\u003csup\u003e\u003cem\u003e+\u003c/em\u003e\u003c/sup\u003e ions to the electrode\u0026rsquo;s \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e surface restricts the amount of current that can travel through the electrode. The concentration gradient close to the electrode affects the diffusion flux. The concentration gradient is then influenced by the rate of solution diffusion. The concentration of the species at the electrode surface also changes when the cell voltage does. A higher current result from a faster voltage sweeps because a higher concentration gradient is created close to the electrode. The impact of scan rate on the peak current for a \u003cem\u003eCV\u003c/em\u003e experiment is described by the Randles-Evk equation. [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e] The diffusion coefficient of the electroactive species can be calculated using the relationships established by this equation. Evidence for a chemical redox process between the electrode and the electrolyte can be found in linear graphs of \u003cem\u003eI vs. v\u003c/em\u003e\u003csup\u003e\u003cem\u003e1/2\u003c/em\u003e\u003c/sup\u003e. (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e)\u003c/p\u003e\n\u003cdiv id=\"Equ6\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equ6\" class=\"mathdisplay\"\u003e$$I=2.69.{10}^{5}\\times {n}^{\\frac{3}{2}}\\times S\\times C\\times {D}^{\\frac{1}{2}}\\times {v}^{\\frac{1}{2}}\\times {\\beta }^{\\frac{1}{2}}$$\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003e8\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eWhere \u003cem\u003eS\u003c/em\u003e is the electrode area in \u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e, \u003cem\u003eF\u003c/em\u003e is the Faraday constant in \u003cem\u003eC/mol\u003c/em\u003e, \u003cem\u003eD\u003c/em\u003e is the diffusion coefficient in \u003cem\u003ecm\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e/s\u003c/em\u003e, and \u003cem\u003eI\u003c/em\u003e is the maximum current in amps. \u003cem\u003en\u003c/em\u003e is typically the number of electrons transferred in the redox event. \u003cem\u003eC\u003c/em\u003e stands for concentration in \u003cem\u003emoles/cm\u003c/em\u003e\u003csup\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sup\u003e, \u003cem\u003ev\u003c/em\u003e for scan speed in \u003cem\u003eV/s\u003c/em\u003e, \u003cem\u003eR\u003c/em\u003e for gas constant in \u003cem\u003eJ/Kmol\u003c/em\u003e, \u003cem\u003e\u0026beta;\u003c/em\u003e for charge transfer coefficient, and \u003cem\u003eT\u003c/em\u003e for temperature in \u003cem\u003eK\u003c/em\u003e. The constant has units of \u003cem\u003eCmol\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eV\u003c/em\u003e\u003csup\u003e\u003cem\u003e1/2\u003c/em\u003e\u003c/sup\u003e and a value of 2.69.10\u003csup\u003e5\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe diffusion coefficient of the electroactive species can be calculated using the relationships established by the Eq.\u0026nbsp;(\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e). According to Eq.\u0026nbsp;(\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e), the \u003cem\u003eK\u003c/em\u003e\u003csup\u003e\u003cem\u003e+\u003c/em\u003e\u003c/sup\u003e diffusion coefficients for the charge process were calculated to be 1.17.10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e, 1.95.10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e, 3.6.10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e, and 2.88.10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003ecm\u003csup\u003e2\u003c/sup\u003e/s for undoped, 2, 4, 6% respectively. The ionic diffusion in the bulk material would be optimized by the co-doped 4% material\u0026rsquo;s appropriately large surface area. Thus, it is reasonable to conclude that a larger surface area and a higher \u003cem\u003eD (K\u003c/em\u003e\u003csup\u003e\u003cem\u003e+\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e)\u003c/em\u003e value may account for the improved rate performance since they would facilitate a quicker potassium ion transfer procedure.\u003c/p\u003e\n\u003cp\u003eThe specific capacitance of the undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped electrode is depicted in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e as a function of the voltage scan rate (Eq.\u0026nbsp;(\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). The results show that (\u003cem\u003eMn, Zn\u003c/em\u003e) co-dopants improve the specific capacitance of electrodes based on \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e. (\u003cem\u003eMn, Zn\u003c/em\u003e) 4% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e displays a higher specific capacitance of \u0026asymp;\u0026thinsp;23.72\u003cem\u003eF/g\u003c/em\u003e at 5\u003cem\u003emV /s\u003c/em\u003e, which is about 30% higher than the value found for undoped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e (\u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003esp\u003c/em\u003e\u003c/sub\u003e \u0026asymp; 13\u003cem\u003eF/g\u003c/em\u003e). Since the ion movement is restricted to the electrode material\u0026rsquo;s surfaces under these circumstances, the specific capacitance remained almost constant for higher scan rates (\u0026gt;\u0026thinsp;50\u003cem\u003emV/s\u003c/em\u003e). In this case, the EDLC dominates the other mechanisms. At lower scan speeds (\u0026lt;\u0026thinsp;50\u003cem\u003emV/s)\u003c/em\u003e, the majority of the active surface is utilized by the ions for charge storage, leading to a larger specific capacitance. The reversibility of the reaction that occurs during the charge and discharge processes is defined by coulombic efficiency (\u003cem\u003eCE\u003c/em\u003e). It is the ratio between the charges generated during the charging and discharging processes.\u003c/p\u003e\n\u003cdiv id=\"Equ7\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equ7\" class=\"mathdisplay\"\u003e$$CE=\\frac{{Q}^{-}}{{Q}^{+}}.100$$\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003e9\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eCoulombic efficiency of undoped and co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e samples at different scan rates.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eSamples\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eCE (0%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eCE (2%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eCE (4%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eCE (6%)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5mV/s\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e89\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e86\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e85\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e85\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10mV/s\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e96\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e89\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e90\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e90\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e50mV/s\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e96\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e94\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e92\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e92\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e100mV/s\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e98\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e96\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e92\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e92\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e150mV/s\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e96\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e96\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e94\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e100\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e200mV/s\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e95\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e95\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e95\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThe \u003cem\u003eCE\u003c/em\u003e is approaching 100% for all samples and for various scan rates, which indicates the absence of irreversible modification of the electrode and also the absence of electrolyte decomposition at the \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e surface. (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e) The \u003cem\u003eGCD\u003c/em\u003e tests carried out in the voltage window of 0.0 to 0.7\u003cem\u003eV\u003c/em\u003e at various current density between 2 and 8\u003cem\u003eA/g\u003c/em\u003e are shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003eThe \u003cem\u003eCV\u003c/em\u003e curves and the non-linearity between potential and time suggest that the examined materials\u0026rsquo; capacitance is not constant over the potential ranges during both charge and discharge cycles. The GCD curves display a pseudocapacitive behavior of the electrode originating from the electrochemical redox reaction on the electrode/electrolyte interface.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eSpecific capacity, energy density, and power density of undoped and co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e at a current density of 2\u003cem\u003eA/g\u003c/em\u003e.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e2\u003cem\u003eA/g\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e\u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003edischage\u003c/em\u003e\u003c/sub\u003e \u003cem\u003e(s)\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eC\u003csub\u003esp\u003c/sub\u003e \u003cem\u003e(F/g)\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eE\u003csub\u003eg\u003c/sub\u003e \u003cem\u003e(Wh/kg)\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eP\u003csub\u003eg\u003c/sub\u003e \u003cem\u003e(Wkg\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e)\u003c/em\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0%\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e2.92\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e8.34\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e2.04\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e2520\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2%\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e3.74\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e10.68\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e2.62\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e2520\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4%\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e6.94\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e19.82\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e4.85\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e2520\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6%\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e4.69\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e13.4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e3.28\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e2520\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThe results show an improvement of the electrochemical properties with the doping in terms of specific capacity and energy density (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e), (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). The best performance was obtained for 4wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e, achieving a specific capacitance of 19.82\u003cem\u003eF/g\u003c/em\u003e, power density and energy density of 2520\u003cem\u003eWkg\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u003c/em\u003e\u0026thinsp;1\u003c/sup\u003e, and 4.85\u003cem\u003eWhkg\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e respectively at 2\u003cem\u003eA/g\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e dipects Nyquist plots for undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e electrodes at open circuit potential. In the higher frequency range, a muted semicircle is present, preceded by an ascending line in the lower frequency region, where their behaviors are primarily capacitive. The depressed semicircles often signify minor resistances to charge exchange between electrode and electrolyte. The diameter of the semicircle represents the kinetic resistance to the ion transfer, known as charge transfer resistance of the redox reactions. At the low-frequency region, the inclined line is related to solid-state diffusion of positive ions in the electrode materials. [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e] Experimental impedance results are analyzed by curve fitting (using OrigaMaster software) to an appropriate electrical equivalent circuit. The Randles circuit of electrode consists of the electrolyte resistance \u003cem\u003eR1\u003c/em\u003e in series with the parallel combination of the double-layer capacitance \u003cem\u003eC2\u003c/em\u003e and impedance Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e EIS of undoped and (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e accompanied by their corresponding equivalent circuit. \u003cem\u003eW1\u003c/em\u003e and charge transfer resistance \u003cem\u003eR2\u003c/em\u003e, as indicated in the inset of Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e. Moreover, for all samples, \u003cem\u003eW1\u003c/em\u003e represents the Warburg impedance evidencing by the 45-degree line which indicates the diffusion of \u003cem\u003eK\u003c/em\u003e\u003csup\u003e\u003cem\u003e+\u003c/em\u003e\u003c/sup\u003e though a semi-infinite medium. The \u003cem\u003eR2\u003c/em\u003e is rather low for (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped 4wt% \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e, 301\u003cem\u003emΩ\u003c/em\u003e, which is attributed to the improved ionic conduction and electrolyte diffusion through the surface asperities of the electrode material.\u003c/p\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eIn this work, undoped and (Mn, Zn) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e thin films were synthesized on nickel foam by spray pyrolysis. \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e phase was confirmed by Raman spectroscopy. It was found that the co-doping induced a Raman shift and broadening of the peaks. The morphological analysis indicated good uniformity of the coating for all the samples, with an overgrown agglomeration of irregular granular structure observed for the co-doping 4wt% sample. Furthermore, EDX mappings confirm the presence of \u003cem\u003eZn\u003c/em\u003e and \u003cem\u003eMn\u003c/em\u003e dopants in a higher proportion by increasing the concentration. Regarding electrochemical analysis, an improvement of the electrochemical properties with doping in terms of specific current, specific capacity, and charge electron transfer. The best performance was obtained for 4wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e5, achieving 23.72\u003cem\u003eF/g\u003c/em\u003e at scan rate of 5\u003cem\u003emV/s\u003c/em\u003e, power density and energy density of 2520\u003cem\u003eWkg\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e, and 4.85\u003cem\u003eWhkg\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e respectively at 2\u003cem\u003eA/g\u003c/em\u003e.\u003c/p\u003e"},{"header":"Declarations","content":" \u003ch2\u003eConflicts of interest\u003c/h2\u003e \u003cp\u003eThere are no conflicts to declare.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThe authors thank \u0026ldquo;Agence universitaire de la Francophonie (AUF)\u0026rdquo; for the Eugen Ionescu research scholarship (H. GHANNAM). The electrode elaboration and characterization were performed at the Materials, Systems and Energy Engineering Laboratory (MaSEEL), ERCMN, (UAE/U01FST).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eH. Ghannam: conceptualization, formal analysis, methodology, data curation, writing \u0026ndash; original draft, visualization, project administration.Z. Rossi: formal analysis, investigation, visualization, writing \u0026ndash; review \u0026amp; editing.S. Haloui formal analysis, investigation, visualization.A. Aouni: investigation, resources, data curation, formal analysis, writing \u0026ndash; review \u0026amp; editing, visualization.A. Elmouwahidi: investigation, visualization, writing \u0026ndash; review \u0026amp; editing.T. Tite: formal analysis, investigation, visualization, writing \u0026ndash; review \u0026amp; editing.M. Diani: investigation, resources, data curation, formal analysis, writing \u0026ndash; review \u0026amp; editing, visualization.A. Chahboun: investigation, resources, writing \u0026ndash; review \u0026amp; editing, visualization, supervision, project administration.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003ePoonam, K. Sharma, A. Arora and S. Tripathi, Journal of Energy Storage, 2019, 21, 801\u0026ndash;825.\u003c/li\u003e\n\u003cli\u003eY. Zhang, H. Feng, X. Wu, L. Wang, A. Zhang, T. Xia, H. Dong, X. Li and L. Zhang, International Journal of Hydrogen Energy, 2009, 34, 4889\u0026ndash;4899.\u003c/li\u003e\n\u003cli\u003eG. Wang, L. Zhang and J. Zhang, Chem. Soc. Rev., 2012, 41, 797\u0026ndash;828.\u003c/li\u003e\n\u003cli\u003eH. Ghannam, J. P. B. Silva and A. Chahboun, RSC Adv., 2021, 11, 23346\u0026ndash;23354.\u003c/li\u003e\n\u003cli\u003eH. Qin, S. Liang, L. Chen, Y. Li, Z. Luo and S. Chen, Sustainable Energy Fuels, 2020, 4, 4902-4933.\u003c/li\u003e\n\u003cli\u003eB. Conway, V. Birss and J. Wojtowicz, Journal of Power Sources, 1997, 66, 1\u0026ndash;14.\u003c/li\u003e\n\u003cli\u003eK. Shireesha and S. C. Chidurala, Applied Surface Science Advances, 2022, 12, 100329. https://doi.org/10.1016/j.apsadv.2022.100329\u003c/li\u003e\n\u003cli\u003eR. N. Reddy and R. G. Reddy, Journal of Power Sources, 2006, 156, 700\u0026ndash;704.\u003c/li\u003e\n\u003cli\u003eG. Wee, H. Z. Soh, Y. L. Cheah, S. G. Mhaisalkar and M. Srinivasan, J. Mater. Chem., 2010, 20, 6720\u0026ndash;6725.\u003c/li\u003e\n\u003cli\u003eC. Delmas, H. Cognac-Auradou, J. Cocciantelli, M. Menetrier and J. Doumerc, Solid State Ionics, 1994, 69, 257\u0026ndash;264.\u003c/li\u003e\n\u003cli\u003eA. Jovanovic, A. S. Dobrota, L. D. Rafailovic, S. V. Mentus, I. A. Pasti, B. Johansson and N. V. Skorodumova, Phys. Chem. Chem. Phys., 2018, 20, 13934\u0026ndash;13943.\u003c/li\u003e\n\u003cli\u003eD. Vernardou, I. Marathianou, N. Katsarakis, E. Koudoumas, I. Kazadojev, S. O\u0026acirc; ̆A ́ZBrien, M. Pemble and I. Povey, Electrochimica Acta, 2016, 196, 294\u0026ndash;299.\u003c/li\u003e\n\u003cli\u003eH. Yu, X. Rui, H. Tan, J. Chen, X. Huang, C. Xu, W. Liu, D. Y. W. Yu, H. H. Hng, H. E. Hoster and Q. Yan, Nanoscale, 2013, 5, 4937\u0026ndash;4943.\u003c/li\u003e\n\u003cli\u003eY. Qiu, Z. Yan, Z. Sun, Z. Guo, H. Liu, B. Du, S. Tian, P. Wang, H. Ding and L. Qian, Inorganics, 2023, 11(3), 118. https://doi.org/10.3390/inorganics11030118 \u003c/li\u003e\n\u003cli\u003eM. Giorgetti and M. Berrettoni, Chemistry of Materials, 2007, 19, 5991\u0026ndash;6000.\u003c/li\u003e\n\u003cli\u003eS. Guan, Y. Wei, J. Zhou, J. Zheng and C. Xu, Journal of The Electrochemical Society, 2016, 163(7), H541-H545. https://doi.org/10.1149/2.0761607jes\u003c/li\u003e\n\u003cli\u003eS. Zhan, C. Wang, K. Nikolowski, H. Ehrenberg, G. Chen and Y. Wei, Solid State Ionics, 2009, 180, 1198\u0026ndash;1203.\u003c/li\u003e\n\u003cli\u003eX. Peng, Z. Zou, W. Ling, F. Liang, J. Geng, S. Zhang and S. Zhong, Nanotechnology, 2023, 34, 235602. https://doi.org/10.1088/1361-6528/acbeb5\u003c/li\u003e\n\u003cli\u003eN. S. Kumar, J. H. Chang, M.-S. Ho, B. Balraj, S. Chandrasekar, B. Mohanbabu, M. Gowtham, D. Guo and K. Mohanraj, Journal of Inorganic and Organometallic Polymers and Materials, 2020, 31, 1066 \u0026ndash; 1078.\u003c/li\u003e\n\u003cli\u003eKumar, N.S., Chang, J.H., Ho, MS. et al. Impact of Zn2+ Doping on the Structural, Morphological and Photodiode Properties of V2O5 Nanorods. J Inorg Organomet Polym 31, 1066\u0026ndash;1078 (2021). https://doi.org/10.1007/s10904-020-01751-y\u003c/li\u003e\n\u003cli\u003eS. K. Rai, R. Rai, R. Bairy, M. Murari, A. Jayarama and R. Pinto, Materials Today: Proceedings, 2021, 35, 469\u0026ndash;473.\u003c/li\u003e\n\u003cli\u003eH. Zeng, D. Liu, Y. Zhang, K. A. See, Y.-S. Jun, G. Wu, J. A. Gerbec, X. Ji and G. D. Stucky, Chemistry of Materials, 2015, 27, 7331\u0026ndash;7336.\u003c/li\u003e\n\u003cli\u003eF. Urena-Begara, A. Crunteanu and J.-P. Raskin, Applied Surface Science, 2017, 403, 717\u0026ndash;727.\u003c/li\u003e\n\u003cli\u003eR. Guidelli, R. G. Compton, J. M. Feliu, E. Gileadi, J. Lipkowski, W. Schmickler and S. Trasatti, Pure and Applied Chemistry, 2014, 86, 245\u0026ndash;258.\u003c/li\u003e\n\u003cli\u003eA. Sevc\u0026iacute;k, Collection of Czechoslovak Chemical Communications, 1948, 13, 349\u0026ndash;377. https://doi.org/10.1135/cccc19480349\u003c/li\u003e\n\u003cli\u003eW. Gomes and D. Vanmaekelbergh, Electrochimica Acta, 1996, 41, 967\u0026ndash;973.\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":"","lastPublishedDoi":"10.21203/rs.3.rs-3856870/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3856870/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eVanadium oxides have been investigated for their potential use in electrochemical supercapacitors due to their variable oxidation states yielding surface redox. However, its electrochemical performance is limited by its poor electronic and ionic conductivity. In an attempt to improve the electronic conductance and electrochemical performance of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e, (\u003cem\u003eMn, Zn\u003c/em\u003e) co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e is investigated. (\u003cem\u003eMn, Zn\u003c/em\u003e) (2, 2) wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e provides the high specific capacitance, it achieves 23.72\u003cem\u003eF/g\u003c/em\u003e at a scan rate of 5\u003cem\u003emV/s\u003c/em\u003e, and it is characterized by very low charge transfer resistance (301\u003cem\u003emΩ\u003c/em\u003e). At 2\u003cem\u003eA/g\u003c/em\u003e current density, its power density and energy density are about 2520\u003cem\u003eWkg\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003e, and 4.85\u003cem\u003eWhkg\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e\u003c/sup\u003erespectively. Because of its good electrochemical performance, (\u003cem\u003eMn, Zn\u003c/em\u003e) (2, 2) wt% co-doped \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e has great application prospects in supercapacitors.\u003c/p\u003e","manuscriptTitle":"Effect of Manganese and Zinc co-dopants on electrochemical properties of vanadium oxide (V2O5) based electrode: application for supercapacitor","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-15 21:04:59","doi":"10.21203/rs.3.rs-3856870/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":"6d21a927-fdb2-4aab-95bf-50d24c6c1b09","owner":[],"postedDate":"January 15th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-06T14:59:00+00:00","versionOfRecord":[],"versionCreatedAt":"2024-01-15 21:04:59","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3856870","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3856870","identity":"rs-3856870","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}