Cationic disordered rock salt composite material as well as preparation method and application thereof

The invention discloses a cation disordered rock salt composite material which is mainly composed of a lithium-rich rock salt phase compound A, a rock salt phase compound B and a small amount of layered phase compounds C. The chemical general formula of the rock salt phase compound A is Li < 1 + x > Mn < y > M < y > 'O < 2-z > F < z >, the chemical general formula of the rock salt phase compound B is LiMnO < 2-a > F < a >, and the chemical general formula of the layered phase compounds C is LiMnO < 2-b > F < b >. The invention also discloses two preparation methods for synthesizing the cation disordered rock salt composite material, namely a molten salt method and a solid-phase synthesis method, and a lithium ion battery taking the cation disordered rock salt composite material as a positive electrode material. The lithium-rich rock salt phase compound A, the manganese-based rock salt phase compound B and a small amount of the layered phase compound C in the cation disordered rock salt composite material are