层状锂镍钴锰氧化物正极材料的改性研究进展

Progress in Modification of Layered Cathode Material Li-Ni-Co-Mn-O

过渡金属(Ni,Co,Mn)氧化物、氢氧化物或碳酸盐前驱体与锂盐经高温焙烧形成的固溶态层状锂镍钴锰氧化物正极材料,具有高放电比容量、低成本等一系列优点,成为研究的热点,并开始广泛应用。然而锂镍钴锰氧化物正极材料在安全性、循环性等方面仍需改善,尤其是在高电压、高温度和高倍率下的充放电性能有待进一步提高。很多研究结果已证明表面包覆和体相掺杂是改善正极材料电化学性能的有效方法。通过表面包覆改性可阻止电极材料与电解液的直接接触,抑制循环过程中HF对电极材料的侵蚀,减少电极材料与电解液的副反应,降低电池在充放电过程中的电荷转移电阻,可进一步提高材料的高倍率电化学性能;而引入掺杂离子可以提高晶体晶格能,稳定材料结构,可提高材料的循环性能。本文对锂镍钴锰氧化物正极材料表面包覆和掺杂的研究现状进行了较全面的分析和总结,并对今后的研究方向提出展望。

Recently, solid solution state of layered Li-Ni-Co-Mn-O cathode materials synthesized by sintering transition metal （ Ni, Co, Mn） oxide, hydroxide or carbonate precursor with lithium compounds at high temperature became the research focus of cathode materials for lithium ion batteries owing to their higher capacity and better safety. However, as a lithium ion battery cathode, the cycle performance of Li-Ni-Co-Mn-O materials should be improved, especially in the charge-discharge performance under high voltage, high temperature and high rates. Many research results proved that surface coating and doping were effective ways to improve the electro- chemical performance of cathode material. It was confirmed that surface coating could prevent the direct contact of electrode from elec- trolyte, and thus suppressed the undesirable interaction between them and the dissolution of transition metal ions attacked by HF acid, and hence, the higher rate performances were enhanced further. Doping could improve the crystal lattice energy, stabilize structure, so as to improve the cycle performance of the material. This paper comprehensively reviewed the research status on the surface coating and the doping of the Li-Ni-Co-Mn-O cathode materials, and proposed the further research direction.