活性炭基Li2SO4水系电解液超级电容器

采用中性Li2SO4水溶液代替H2SO4和KOH作为电解液制备了活性炭(AC)基对称型超级电容器,使水系超级电容器的工作电压由1.0V提高到了1.6V.采用循环伏安和充放电测试研究了电容器的稳定电化学窗口.电化学充放电测试表明电容器在0.25A.g-1电流密度下单电极比容量可达129F.g-1,在功率密度为160W.kg-1时能量密度达到10Wh.kg-1(以正负极活性物质的总质量计).1.6V恒压充电1h后电容器漏电流为0.22mA.超级电容器的库仑效率接近100%,充放电循环5000次后容量仍可保持在92%以上.研究了电解液的浓度对电容器电化学性能的影响,发现随着Li2SO4浓度的增大电容器的电荷转移电阻显著减小,大电流充放电性能提高.活性炭基Li2SO4水系电解液超级电容器具有工作电压高、能量密度高和对环境友好等优点,因此有很好的产业化前景.

Activated Carbon-Based Supercapacitors Using Li2SO4 Aqueous Electrolyte

In this work,we prepared activated carbon-based symmetric supercapacitors using Li2SO4 aqueous electrolyte instead of H2SO4 and KOH,and obtained devices with an improved working voltage of 1.6 V from 1.0 V.Cyclic voltammetry and galvanostatic charging/discharging measurements were used to study the electrochemical properties.The results showed that the electrode specific capacitance can reach 129 F.g-1,and the energy density can be as high as 10 Wh.kg-1 at a power density of 160 Wh.kg-1.Electrochemical impedance analysis measurements showed that the charge-transfer resistance of the capacitors decreased markedly with the increase of the concentration of Li2SO4,and the rate capability improved accordingly.The leakage current of the supercapacitor was 0.22 mA after constant-voltage charging at 1.6 V for 1 h,and the columbic efficiency was nearly 100%.The capacitance of the supercapacitor remained above 90% after 5000 charge-discharge cycles.Activated carbon-based supercapacitors using Li2SO4 aqueous electrolyte have many advantages,such as high working voltage,high energy density,and environmental compatibility,and therefore have good industrialization prospects.