Improving the cycling stability of Ni-rich cathode materials by fabricating surface rock salt phase

Mo doped Ni-rich LiNi_0.8Co_0.1Mn_0.1O₂ cathode materials have been synthesized via coprecipitation followed by high-temperature solid state method. The effect of Mo doping on the structure, morphology, and electrochemical performances of Ni-rich cathode material has been investigated. The results reveal that Mo doping may promote the formation of surface rock salt phase and expand the Li⁺ diffusion channels for Ni-rich material. Benefit from which, the further transition of layered to rock salt structure during cycling has been alleviated. As a result, the optimal Mo doped material, with 1 wt% doping, exhibits enhanced cycling stability with superior electrochemistry performances, that is high reversible capacity of 215.7 mAh g⁻¹ at 0.1C, and 184.1 mAh g⁻¹ at 1C with an excellent 100^th capacity retention of 92.4%. Even the cut-off voltage raises to 4.5 V, the 100^th capacity retention of Mo-doped material still reaches as high as 85.2%. The results indicate that fabricating the Ni-rich materials with a surface rock salt phase is an effective strategy towards better structure stability and electrochemical performances.