Abstract:

Increasing the driving range of EVs depends on the energy density of lithium-ion batteries, of which the cathode material plays a key role. High-capacity cathode materials such as lithium-rich layered oxides and high nickel materials(Ni≥80%) have become research hotspots, and their precursors have a great influence on the electrochemical performance of cathode materials. This review introduced the reaction process and influencing factors of the co-precipitation method for preparing lithium-rich and high-nickel cathode precursors. The structure and performance of cathode materials such as spherical aggregates, single crystals and concentration gradients were introduced in detail. The principles, advantages and disadvantages of modification strategies such as crystal orientation adjustment, doping and surface/interface treatment in cathode materials were described. In a comprehensive, single crystals can improve cycle life and thermal stability, but the rate performance needed to be further improved. The concentration gradient cathode material not only delivered the high capacity but also kept structural stability and thermal stability, which was expected to break through the bottleneck of the further development of high-capacity cathode materials. Finally, based on the detailed research of our group on high-capacity cathode materials, some suggestions were given for the research directions of cathode materials.

Key words: co-precipitation, precursors, high-capacity cathode materials, lithium-ion batteries

摘要：

电动汽车续航里程的提升主要依赖于锂离子电池的能量密度，其中发展高容量的正极材料成为关键。富锂锰基层状氧化物（LLOs）和高镍三元层状氧化物（NCM，Ni≥80%）等高容量正极材料成为了研究热点，其前体的开发对正极材料电化学性能的发挥有重要的影响。本文从工业化的角度对共沉淀法制备LLOs和NCM正极材料前体的反应过程和影响因素进行了介绍，分析了球形团聚体、单晶和浓度梯度等正极材料的结构和性能，并详细阐述了正极材料中晶面取向调控、掺杂及表界面处理等改性策略的原理及优缺点。文章指出，综合来看单晶材料表现出较好的循环稳定性和热稳定性，但倍率性能有待进一步提升。浓度梯度正极材料不仅保持了高容量特性，还兼顾良好的结构稳定性和热稳定性，有望突破高容量正极材料进一步发展的技术瓶颈。最后，基于本文作者课题组在高容量正极材料方面的研究，对正极材料的未来发展趋势给出了一些建议。

关键词: 共沉淀, 前体, 高容量正极材料, 锂离子电池