超级电容器混合型电解液(EMIES+LiClO_4)的热力学和电化学性质

Thermodynamics and electrochemistry properties of supercapacitor mixed electrolyte(ethylsulfate ionic liquids + lithium perchlorate)

介绍了一种新型离子液体混合电解质(液),由离子液体1-乙基-3-甲基咪唑硫酸乙酯盐(EMIES)与高氯酸锂盐按照不同配比混合制备而成。测定了这种新型混合电解质(EMIES+Li Cl O_4)的一系列热力学性质,如:电导率、密度、表面张力等,发现其黏度和电导率随温度的变化呈相反趋势。锂盐的加入带来了混合电解液电导率的非线性变化,而当其中高氯酸盐的摩尔比为0.05时,电解液具有最佳电导率和黏度。进而,用此浓度的混合电解液与活性炭电极组装成超级电容器,采用交流阻抗、恒流充放电及循环伏安等测试手段对其性能进行测试与研究。结果表明:这种离子液体混合电解液电化学窗口达到5.1 V,单电极比电容为458.65 F·cm^(-3),充放电测试1000次以后,比电容只下降了1.9%。表明该混合电解液具有良好的电容特性、可逆性及循环特性,具备成为高性能超级电容器电解液的应用潜力。

A series of new ionic liquid-based electrolytes were prepared by mixing ionic liquid1-ethyl-3-methylimidazole ethylsulfate(EMIES)and lithium perchlorate salt(LiClO4)with different molar ratios.The thermodynamic properties of the mixed electrolyte systems(EMIES+LiClO4)were determined like conductivity,density,and viscosity.The viscosity and conductivity of the system show an opposite trend with the temperature change.There is a nonlinear change of the conductivity with the addition of LiClO4for the system,and when the molar ratio of perchlorate is0.05,the electrolyte has a optimal conductivity and viscosity performances.Further,the activated carbon electrode was used to assemble the supercapacitor with the mixed electrolyte.The performances of the assembled supercapacitor weretested and studied by AC impedance,constant current charge-discharge,and cyclic voltammetry methods.The results areas follows:the electrochemical window of the mixed electrolyte reaches5.1V;the single electrode capacitance ratio is458.65F·cm–3;specific capacitance after1000times charge-discharge test decreases only1.9%.Those indicate that thenew mixed ionic liquid-based electrolyte can provide excellent capacitance,good reversibility and cycling characteristics.The mixed electrolyte system has great potential in high performance supercapacitor applications.