Effect of in-situ Zr doping on the crystallization behavior and electrochemical properties of cobalt-free layered LiNi0.8Mn0.2O2 cathode materials

Abstract

Elemental doping is an effective strategy to overcome the degradation of the rate performance of cobalt-free layered cathode materials, which is attributable to the absence of cobalt. This study focuses on the implementation of a modified doping strategy, which entails in-situ coprecipitation to introduce 0.3 mol% Zr4+ as a dopant to these cathode materials. This approach enabled us to confirm that in-situ Zr4+ doping significantly impacted the crystallization behavior and electrochemical properties of these materials and this effect is not negligible. In particular, in-situ Zr4+ doping increased the crystallization temperature of the materials and broadened the spacing between the lithium layers while maintaining the original crystal configuration. The doped sample had the best cycling stability at the crystallization temperature of 800 °C (capacity retention of 80.03% after 200 cycles at the 1 C rate) and rate performance (discharge specific capacity of up to 161.6 mAh g−1 at the 5 C rate), whereas the original (undoped) sample delivered the best electrochemical performance at 780 °C (capacity retention of 74.29% after 200 cycles at the 1 C rate and discharge capacity at the 5 C rate of 154.57 mAh g−1).