Conventional polyanion-based positive active material - graphene composite particles, the contact area of ​​graphene and polyanion-based positive active material is small, it was impossible to obtain a high conductivity.
The present invention Step 1: polyanion-based positive active material precursor and the oxidation of graphite mixed to form a precursor composite granule containing polyanion-based positive active material precursor particles in a graphite oxide process; Step 2: the precursor composite granular material obtained in step 1, in an inert atmosphere or a reducing atmosphere, heating at 500 ° C. or higher; having, a method for producing a polyanion-based positive active material composite particles, the precursor in X-ray diffraction intensity of the body complex granule, the maximum intensity of X-ray diffraction peaks based on the cathode active material, is less than 50% of the maximum intensity of X-ray diffraction peaks based on other than the positive electrode active material, the polyanionic cathode active in X-ray diffraction intensity of the material composite particles, the maximum intensity of X-ray diffraction peaks based on the cathode active material, is 50% or more of the maximum intensity of X-ray diffraction peaks based on other than the positive electrode active material, the polyanion-based positive active material composite the method for producing a body particles.