Enhancing the interfacial stability of LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode materials by a surface-concentration gradient strategy

and decreases the interfacial film impedance. Moreover, less Ni content on the material surface is beneficial for reducing the formation of a NiO rock salt phase during the charging process and inhibits the surface structural evolution. The proposed method and detected mechanism will provide guidance for the design of cathode materials and their practical industrial applications.