石墨/Li(Ni1/3Co1/3Mn1/3)O2电池储存后的衰减机理

摘要

用充放电测试、电化学阻抗(EIS)、循环伏安(CV)、场发射扫描电镜(FE-SEM)和X射线能谱(EDX)等方法,研究了石墨/Li(Ni1/3Co1/3Mn1/3)O2电池高温储存后的性能变化.在55℃下储存后,Li(Ni1/3Co1/3Mn1/3)O2正极的容量衰减较大,同时阻抗增大,动力学性能下降.储存后的容量衰减主要来源于正极,原因是:储存期间电解液中的LiPF6分解,生成的HF侵蚀正极活性材料,同时在表面生成LiF等高阻抗的沉积物.%The performance changing of a graphite/Li(Ni1/3Co1/3Mn1/3)O2 battery after storage at high temperature was studied by charge-discharge tests,electrochemical impedance spectroscopy (EIS),cyclic voltammetry (CV),field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscopy (EDX). After stored at 55 ℃, the Li( Ni1/3Co1/3 Mn1/3)O2 cathode showed larger capacity fading, whose impedance increased and kinetic characteristics decreased. The cathode might contribute to the overall degradation of the battery after storage. The reason was the corrosion of cathode material by HF, which might result from the decomposition of LiPFg.and the precipitation of high resistance products such as LiF on the surface.