METHOD FOR PRODUCING POLYANIONIC POSITIVE ELECTRODE ACTIVE MATERIAL COMPOSITE PARTICLES, AND POLYANIONIC POSITIVE ELECTRODE ACTIVE MATERIAL PRECURSOR-GRAPHITE OXIDE COMPOSITE GRANULATED BODIES

Conventional polyanionic positive electrode active material-graphene composite particles have not been able to achieve high conductivity since the contact area between the graphene and the polyanionic positive electrode active material is small. The present invention is a method for producing polyanionic positive electrode active material composite particles, which comprises: a step 1 wherein precursor composite granulated bodies, each of which contains a polyanionic positive electrode active material precursor particle in graphite oxide, are formed by mixing a polyanionic positive electrode active material precursor and graphite oxide; and a step 2 wherein the precursor composite granulated bodies obtained in step 1 are heated at 500°C or higher in an inert atmosphere or in a reducing atmosphere. With respect to the X-ray diffraction intensity of the precursor composite granulated bodies, the maximum intensity of the X-ray diffraction peak based on the positive electrode active material is less than 50% of the maximum intensity of the X-ray diffraction peak based on the materials other than the positive electrode active material. With respect to the X-ray diffraction intensity of the polyanionic positive electrode active material composite particles, the maximum intensity of the X-ray diffraction peak based on the positive electrode active material is 50% or more of the maximum intensity of the X-ray diffraction peak based on the materials other than the positive electrode active material.