层状高镍材料因能量密度高和成本低的优点成为目前最有应用前景的锂离子动力电池正极材料，然而高镍材料面临化学稳定性不足，特别是空气敏感效应等挑战。针对目前空气敏感机理的局限，项目通过原位拉曼研究高镍薄膜材料在空气中表界面结构和成分变化，深层次揭示材料空气敏感机理。基于此，采用固相法对高镍材料进行LiTi2(PO4)3-Li3PO4原位包覆和Ti4+界面梯度掺杂的多尺度修饰来提高材料稳定性。Ti4+掺杂提高Ni3+/2+电对电势，增加材料界面电势，与防水包覆层协同增强高镍材料空气稳定性。Ti4+对充电态高镍中Ni4+进行电子补偿，抑制Ni4+/Ni2+转变；Li3PO4与电解液中HF、H2O反应，生成物附着在材料表面形成人造SEI膜；LiTi2(PO4)3抑制材料与电解液副反应；三者共同作用改善材料电化学性能。本项目材料空气敏感效应和表界面多尺度修饰的研究为其他材料表界面稳定性研究提供新思路。

The layered nickel-rich materials have been regarded as one of the most promising cathode candidate for lithium ion batteries for EVs due to the advantage of high energy density and low cost. However, they still have many difficulties in the commercialization with respect to chemical stability, especially for the air sensibility. Due to the limitation of the mechanism of air sensibility, in-situ Raman spectroscopy will be used in this proposal to study the evolution of surface chemistry of nickel-rich film during storage in air. Based on the chemical information inferred by spectroscopic features, the mechanism of the air sensibility is expected to be unraveled. Based on the mechanism, the multi-scale modification constructed by the in-situ coating of LiTi2(PO4)3-Li3PO4 and the gradient doping of Ti and the controllable synthesis will be investigated. Taking the advantage of the synergistic effect between Ti gradient doping, which is believed to can increase of Ni3+/2+, and LiTi2(PO4)3-Li3PO4 coating, the surface potential and air stability of the material will be enhanced. Ti doping can also play as electron compensator of Ni4+ at charge state, which can restrain the conversion of Ni4+/Ni2+ and then can improve the structural stability. Furthermore, Li3PO4 will consume the H2O and HF in electrolyte and the corresponding products will act as artificial SEI layer due to the similar component. The accomplishment of the project will be of great importance regarding to the study of air sensibility and multi-scale modification construction for other battery materials.