导电剂形貌对富锂正极材料性能发挥的影响

研究了纳米颗粒状的Super P、气相生长的碳纤维(VGCF)、片状的KS6和石墨烯四种不同的导电剂对富锂正极材料Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_2(LR-MNC)的电化学性能发挥的影响。研究结果表明,当导电剂的添加量为10%(质量分数),以Super或VGCF的导电剂在活性材料的表面形成了完整的导电通路,电极的表面电阻最小,从而有利于电子的传输,因此,正极活性物质表现出优异的倍率放电性能和循环性能。其中,以Super P为导电剂的电极性能最优,3 C放电比容量为164.4 mAh/g,1 C循环100周,容量保持率为82.3%。而以片状的KS6或石墨烯单独作为导电剂,在电极中没有形成完整的导电通路,不利于正极活性物质的大倍率放电性能的发挥。

Effect of conductive agents with different morphology on electrochemical performance of Li-rich solid solution cathode materials

The effect of four kinds of conductive agents,namely Super P nano particles,vapor grown carbon fibers (VGCF),flake-like KS6 and graphene,on the electrochemical performance of Li-rich solid solution materials Li1.2Mn0.54Ni0.13Co0.13O2(LR-MNC) was investigated in this article.The results indicate that the morphology of conductive agents plays an important role on the electrochemical properties of the materials.When the content of conductive agents is 10％,nano-particles or fibers of conductive agents around the active materials form complete conductive pathway and the electrodes has lower impendence.It is favor to the transfer of electrons.Therefore,the cathodes have excellent rate and cycle performance uses Super P or VGCF as conductive agents.Furthermore,the performance of the materials is highest by Super P,which is that the discharge capacity is 164.4 mAh/g at 3 C and the capacity retention cycled 100th at 1 C is 82.3％.However,it does not form complete conductive pathway with flake-like KS6 or graphene as conductive agents.This is not conducive to the properties of the cathodes at high rates.