高镍正极材料表面锂残渣的研究进展

Research progress on the surface lithium residue of high-nickel cathode materials

目前锂离子电池的电化学性能和成本在很大程度上取决于正极材料,其中,具有高比容量和高工作电压等优点的高镍层状正极材料被广泛关注。然而,其表面的锂残渣会严重影响电极的制备和电池的电化学性能,限制了其在新能源汽车等领域的大规模应用。因此,高镍层状正极材料表面锂残渣的研究在进一步提升材料性能和电池安全性能等方面具有重要意义。本文综述了近年来高镍层状正极材料表面锂残渣的研究进展,从锂残渣形成机理,对高镍层状正极材料的影响以及酸碱滴定、傅里叶红外光谱、飞行时间二次离子质谱、固态核磁共振及热重分析结合质谱等锂残渣含量检测方法方面展开,总结了利用去除、物理包覆及原位再利用三种方法有效消除锂残渣对高镍层状正极材料的影响,改善其性能,并对进一步消除锂残渣对正极材料及锂离子电池的影响进行了展望。同时,本文针对锂残渣的展望及研究也同样适用于钠离子电池正极材料表面的钠残渣。本文旨在突出锂残渣原位再利用在高镍层状正极材料改性研究中的应用潜力,为锂离子电池的研究发展提供新的思路。

Currently,the electrochemical performance and cost of lithium-ion batteries(LIBs)are mainly dependent on their cathode materials,among which high-nickel layered cathode materials with large specific capacities and high operating voltages are widely popular.However,the surface lithium residue would seriously influence the preparation of electrodes and the electrochemical performances of batteries,thus limiting their large-scale applications in new energy vehicles and other fields.Therefore,the study of surface lithium residue of high-nickel layered cathode materials is essential to further improve the material properties and battery safety.In this review,the research progress on surface residual lithium compounds(RLCs)of high-nickel layered cathode materials in recent years has been summarized,including the formation mechanism of lithium residue,influence of RLCs for high-nickel layered cathode materials,and detection methods(such as acid-base titration,Fourier infrared spectroscopy,time-of-flight secondary ion mass spectrometry,solid-state nuclear magnetic resonance,and thermogravimetric analysis combined with mass spectrometry)of content.Moreover,three modified methods for effectively eliminating the influence of RICs on high-nickel layered cathode materials are classified into removal,physical coating,and in-situ reuse,thereby improving their performance.Finally,the effect of further elimination of lithium residue on cathode materials and LIBs has been prospected.Meanwhile,the prospect and research on lithium residue are also applicable to the sodium residue on the surface of cathode materials of sodium-ion batteries.This review aims to highlight the application potential of the in-situ reuse of lithium residue in the modification of high-nickel layered cathode materials,thus providing new ideas for the development of LIBs.