POSITIVE ELECTRODE MATERIAL AND PREPARATION METHOD THEREOF, POSITIVE ELECTRODE SHEET AND ALL-SOLID-STATE BATTERY

The present application provides a positive electrode material, a preparation method thereof, a positive electrode sheet and an all-solid-state battery. The positive electrode material includes a lithium-rich manganese-based positive electrode active material and a coating layer covering at least part of a surface of the lithium-rich manganese-based positive electrode active material, where a molecular formula of the lithium-rich manganese-based positive electrode active material is xLiMnO·(−x)LiNiCoMnO, where a+b+c=1, 0