Lithium ion battery composite positive electrode material, preparation method thereof and assembled battery

The invention relates to the technical field of lithium ion batteries, and particularly discloses a lithium ion battery composite positive electrode material, a preparation method thereof and an assembled battery. The preparation method of the lithium ion battery composite positive electrode material comprises the following steps: preparing thin-layer graphene oxide, mixing the graphene oxide with silica sol, carrying out hydrothermal reduction and heat treatment in a nitrogen atmosphere, coating the surface of silicon dioxide with the graphene oxide thin layer, and drying to obtain the lithium ion battery composite positive electrode material. The preparation method comprises the following steps: etching silicon dioxide through hydrogen fluoride to form porous three-dimensional hollow graphene oxide porous spheres, inducing iron octafluorophthalocyanine to grow through oxygen-containing functional groups on the surfaces of the hollow graphene oxide porous spheres to obtain iron octafluorophthalocyanine (at)