掺钴锰酸锂的合成及在水系电解液中的赝电容性能

Synthesis and Pseudo-capacitive Properties of LiMn_2O_4 Doped with Co^(3+) in Aqueous Electrolyte

采用尿素辅助溶胶凝胶法合成了尖晶石型掺钴锰酸锂(L iMn2-xCoxO4,0≤x≤0.3)纳米颗粒.以L iMn2-xCoxO4电极为正极,活性炭(AC)电极为负极,在1 mol.L-1L i2SO4水系电解液中组装成模拟非对称超级电容器AC/L iMn2-xCoxO4,通过循环伏安和恒流充放电法研究其赝电容性能.电化学测试结果表明,随着钴掺杂量的增加,AC/L iMn2-xCoxO4电容器的比电容呈下降趋势,但循环性能得到改善;其中AC/L iMn1.9Co0.1O4电容器展现出较大的比电容和较好的循环性能.在L i2SO4水系电解液中,当工作电压为(0-1.4)V、电流密度为100 mA.g-1时,AC/L iMn1.9Co0.1O4电容器的初始比电容为42.6 F.g-1;经1 000次循环后比电容为40.8 F.g-1,比电容保持率为95.8%.

Spinel LiMn2-xCoxO4（0≤x≤0.3） nanoparticles were synthesized by a sol-gel method using carbamide as chelating agent.Asymmetric supercapacitors were fabricated with LiMn2-xCoxO4 electrode as a positive electrode and activated carbon（AC） as a negative electrode in 1 mol·L-1 Li2SO4 aqueous electrolyte.Pseudo-capacitive properties of AC/LiMn2-xCoxO4 supercapacitors were determined by cyclic voltammetry and charge-discharge test.The AC/LiMn2-xCoxO4 capacitors displayed lower specific capacitance value and yet exhibited better cycling performance with the increase of Co content.AC/LiMn1.9Co0.1O4 supercapacitor showed the best pseudo-capacitive properties in consideration of specific capacitance and cycling performance in all AC/LiMn2-xCoxO4 capacitors.In the potential range of（0-1.4） V,AC/LiMn1.9Co0.1O4 capacitor delivered initial specific capacitance value of 42.6 F·g-1（based on the active mass of the two electrodes） at a current density of 100 mA·g-1 in Li2SO4 solution.After 1000 cycles,specific capacitance remained 40.8 F·g-1,which was 95.8% of initial value.