锂离子电池富镍三元正极材料NCM的研究进展

Research progress of nickel-rich ternary cathode material ncm for lithium-ion batteries

正极材料作为锂离子电池的四大核心材料之一,是锂离子电池电化学性能的决定性因素。其中,富镍三元正极材料LiNi_(x)Co_(y)Mn_(1−x−y)O_(2)(NCM,x≥0.6)因其较高的比容量和卓越的倍率性能等优点被广泛关注,被认为是下一代锂离子电池中最具有发展潜力的正极材料之一。然而,富镍三元正极材料存在的循环稳定性差、热稳定性差以及安全性能低等缺点,限制了其在电动汽车和混合动力汽车等方面的大规模应用。因此,富镍三元正极材料NCM的研究对于完善当前锂离子电池体系有着重要的意义。随着材料制备方法的不断改进,富镍三元正极材料的电化学性能得到了显著的提高。本文综述了近年来富镍三元正极材料的研究进展,依据富镍三元正极材料NCM的晶体结构以及阳离子混排、循环稳定性差、材料表面残碱和表面副反应等失效机理方面展开,重点阐述了通过元素掺杂、表面包覆、掺杂包覆一体化、单晶化、构建核壳结构和浓度梯度的方法对其电化学性能的改善,并对富镍三元正极材料在锂离子电池的应用和未来的研究方向做出展望。

As one of the four basic components of lithium-ion batteries(LIBs),cathode material determines the electrochemical performance of LIBs.Nickel-rich cathode LiNi_(x)Co_(y)Mn_(1−x−y)O_(2)(NCM,x≥0.6)has attracted extensive attention and is considered as one of the most potentially available cathode materials owing to its high specific capacity and excellent rate performance.However,this cathode material type suffers from poor cyclic stability,poor thermal stability,and safety issues,which hinder its extensive practical large-scale application in electric and hybrid electric vehicles.Therefore,research on nickel-rich ternary cathode material NCM is very important for improving the current LIB system.Following the development in fabrication methods,the electrochemical properties of Ni-rich ternary cathode materials have significantly improved.In this study,the recent research progress of Ni-rich ternary cathode materials is reviewed.This work introduces the crystal structure and deterioration mechanisms of NCM cathode materials,such as cation mixing,poor cyclic stability,and residual alkali and by-products on the material surface.This work also summarizes the improvement in NCM cathode materials using element doping,surface coating,integration of doping and coating,construction of single-crystalline materials,and construction of core-shell and gradient structures.Finally,a brief outlook for future research direction and development of nickel-rich ternary layered oxide for LIBs is presented.