共沉积Co_3O_4-石墨负极材料及其在锂离子电池中的循环性能

Co_3O_4-Graphite Negative Electrode Prepared by Co-Electrodeposition and Its Cycling Performance in Lithium-Ion Batteries

在0.5 mol/L Co（NO3）2溶液中添加石墨粉,在铜箔集流体的表面电化学共沉积前驱体薄膜,然后在245℃真空热处理使之形成Co3O4-石墨粉复合负极材料。研究了共沉积Co3O4-石墨负极材料在锂离子电池中的循环性能。XRD分析和SEM观察表明,该电极材料结构由蜂窝状的Co3O4包覆石墨粉复合而成,Co3O4晶粒尺寸为0.7~2.2 nm。0.5C充放电倍率测试表明,在0.5 mol/L Co（NO3）2电解液中添加5%石墨粉形成的Co3O4-石墨复合材料负极的性能最好,该电极的初始充电比容量为872.7 mA.h/g,第20周循环的充电比容量为732.7mA.h/g,第50周循环的充电比容量为545.2 mA.h/g,比容量保持率分别为83.96%和62.47%;而纯Co3O4电极的初始充电比容量为665.3 mA.h/g,经过20次循环后充电比容量为407.9 mA.h/g,第50周循环的充电比容量为124.5mA.h/g,保持率仅分别为61.31%和18.31%。

Co3O4-graphite negative electrode materials was prepared by co-electrodepositing in precursor film 0. 5 mol/L Co （ NO3 ） 2 solution added with different content of graphite powders and then vacuum heat treated at 245 ℃. The cycling performance of the electrode materials was studied. The results show that the electrode materials is composed of Co3O4 and graphite phases with honeycomb structure ,in which average crystal size of Co3O4 is 0. 7 -2.2 nm. Charge-discharge tests at the current of 0.5C show that the best performance is obtained for the Co3O4-graphite composite negative elec- trode with the addition of 5% graphite powder. Its first charge specific capacity is 872. 7 mA.h/g. Its charge specific capacity after 20 cycles and 50 cycles are 732.7 mA. h/g and 545.2 mA. h/g, and capacity retention are 83.96% and 62. 47%, respectively. However, the first charge specific capacity of the pure Co3O4 is only 665.3 mA. h/g, and the capacity retention after 20 cycles and 50 cycles are 61.31% and 18.31% , respectively.