新型LiFePO_4/AC混合超级电容器的制备和性能研究

以橄榄石型磷酸亚铁锂(LiFePO4)为正极,活性炭(AC)为负极,制备了LiFePO4/AC混合超级电容器。通过充放电、倍率和漏电流测试,系统研究了所制混合超级电容器的电化学性能。结果表明,在正负极活性物质质量比为0.8∶1.0的条件下,混合超级电容器综合性能最佳:比容量为25.38 mAh.g–1,比能量为3.21 Wh.kg–1,分别是活性炭超级电容器的2.83倍和2.17倍,且在大倍率充放电下循环稳定性好、漏电流小,在1600 s后漏电流为0.25 mA。

Preparation and research of electrochemical performance of new LiFePO4/AC hybrid supercapacitor

The LiFePO4/AC hybrid supercapacitor using LiFePO4 as positive electrode and the activated carbon(AC) as negative electrode was assembled.Electrochemical performance was studied through testing of charge and discharge,various discharge rates and leakage current.With the mass ratio of 0.8∶1.0 of active materials in the positive electrode and the negative electrode,the results show that the hybrid supercapacitor has the best comprehensive performance.Specific capacity and specific energy of as-prepared supercacpacitors reach 25.38 mAh·g-1 and 3.21 Wh·kg-1,and are 2.83 times and 2.17 times of activated carbon supercapacitor respectively.The hybrid supercapacitors possess good rate charge and discharge properties.Cycle stability of LiFePO4/AC hybrid supercapacitor is fine and leakage current is small under high discharge rates.Leakage current of hybrid supercapacitor is 0.25 mA after 1 600 s.