The Failure Mechanisms and Modification Strategies of Li Ion Battery Ni-based Cathode

With the continuous advancement of the clean energy transition, Lithium-ion batteries are a kind of high-performance energy storage medium. However, high nickel content not only improve capacity of batteries, but also intensifies structure degradation and interface side reaction in the cyclic process, which contributes to capacity fade and decreased safety. This review systematic summarizes the basic structure and electrochemical reaction mechanism of Ni-based layered oxides, and highlights analysis on the primary failure mechanism in high-voltage cycling, which include oxygen release and the form of oxygen vacancy, surface phase transition and cation mixing. On this basis, this review conclude some research advance of mainstream modification strategies, including element doping, which means single anion/cation doping or mixed ion doping were applied to improve crystal lattice stability, restrain cation mixing and increase Li+ migration rate, surface modification, i.e. isolating electrolyte and restraining side reaction or oxygen release by using metal oxides and carbon materials as coating or applying novel surface treatment method, microstructure engineering, i.e. enhancing surface stability and mitigating structure degradation by regulate the intragranular grain shape, size and arrangement to optimize the stability and electrochemical performance of NCM cathodes, especially for polycrystalline materials.