High voltage supercapacitors using hydrated graphene film in a neutral aqueous electrolyte |
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Authors: | Xiaowei Yang Yu-Shi He Gengping Jiang Xiao-Zhen Liao Zi-Feng Ma |
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Institution: | aDepartment of Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China;bDepartment of Materials Engineering, Monash University, VIC 3800, Australia |
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Abstract: | The potential stability windows of chemical converted graphene in different aqueous electrolyte solutions were investigated for the first time. Based on this result, a supercapacitor with a high voltage and long cycle-life was prepared with the hydrated graphene films in the neutral aqueous solution at the maximum voltage of 1.6 and even 1.8 V. The electrochemical performance of the obtained sample was systematically investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. According to the cyclic voltammetry, hydrated graphene film can still retain rectangular shape at the high scan rate of 0.5 V/s in the neutral aqueous electrolyte. At a galvanostatic charge/discharge rate of 1 or 200 A/g, the specific capacitance of 202.3 or 138.1 F/g was delivered, respectively. Furthermore, the EIS results also confirm its fast neutral ion diffusion and high operating frequency of 9.34 Hz. |
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Keywords: | Supercapacitor Potential window Graphene film Neutral electrolyte Voltage |
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