Improving the Thermal Stability of NMC 622 Li-Ion Battery Cathodes through Doping During Coprecipitation

Abstract

Increasing the Ni content of LiNi_<i>x</i>Mn_<i>y</i>Co_{1-<i>x</i>-<i>y</i>}O₂ (NMC) cathodes can increase the capacity, but additional stability is needed to improve safety and longevity characteristics. In order to achieve this improved stability, Mg and Zr were added during the coprecipitation to uniformly dope the final cathode material. These dopants reduced the capacity of the material to some extent, depending on the concentration and calcination temperature. However, these dopants can impart substantial stabilization. It was found that the degree of stabilization is strongly dependent on the calcination temperature of the material. In addition, we used synchrotron X-ray diffraction during thermal breakdown to better understand why the different dopants impact the thermal stability and confirm the stabilization effects of the dopants.