导电剂和粘结剂对高镍正极性能影响分析

Effect of conductive agent and binder on performance of high-nickel cathode

由活性物质、导电剂和粘结剂构成的微区是电极中电化学反应的场所,其离子和电子传递动力学决定了电化学反应的特性。通过改变导电剂和粘结剂的比例和充电截止电压,分析LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)颗粒表面离子和电子迁移环境变化对循环性能的影响;用循环过程中不可逆比容量之和评估了半电池的循环稳定性。结果表明,导电剂或粘结剂的增加有利于改善高镍正极在充电截止电压为4.7 V(vs.Li+/Li)时的循环稳定性,主要原因是导电剂或粘结剂的增加延缓了NCM811裂纹和粉化。

A region composed of active material,conductive agents and binder,where the electrochemical reaction of the electrode occurs,and its ionic and electronic transfer kinetics determines the characteristics of the electrochemical reaction.The effect of variation of ionic and electronic migration environment on the surface of the LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)particles on the cycling performance was analyzed by changing the proportion of conductive carbon and binders and charge cutoff voltage.Furthermore,a new parameter of sum of irreversible specific capacity during the cycling process was adopted to analyze the cycle stability of the half-cell.The results demonstrate that the addition of conductive agents or binder is advantageous in enhancing the cycle stability of high nickel cathodes at high charging cutoff voltage of 4.7 V(vs.Li^(+)/Li),because the cracking and pulverization of NCM811 are delayed by the addition of conductive carbon or binder.