Composite active material, solid state battery and method for producing composite active material

A composite active material comprising an active material, a coat layer with an average thickness of less than 100 nm, formed on a surface of the active material and composed of an ion conductive oxide, and a carbon particle penetrating the coat layer, formed on the surface of the active material.

A producing method for a composite active material, comprising steps of:

• a supporting step of supporting a carbon particle on a surface of an active material to form a carbon particle-supporting active material,
• a precursor active material forming step of forming a precursor active material having a precursor layer on the surface of the active material composing the carbon particle-supporting active material by a fluidized bed coating method while using a coat layer forming solution, and
• a heat-treating step of heat-treating the precursor layer to form a coat layer with an average thickness of less than 100 nm, composed of an ion conductive oxide.

A producing method for a composite active material, comprising a step of:

• a mixed solution forming step of forming a mixed solution containing a carbon particle irradiated with ultraviolet ray and a coat layer forming raw material,
• a precursor active material forming step of forming a precursor active material having a precursor layer and the carbon particle on a surface of an active material by a fluidized bed coating method while using the mixed solution, and
• a heat-treating step of heat-treating the precursor layer to form a coat layer with an average thickness of less than 100 nm, composed of an ion conductive oxide.