COMPOSITE POSITIVE ELECTRODE ACTIVE MATERIAL FOR ALL-SOLID-STATE SECONDARY BATTERY, METHOD FOR MANUFACTURING SAME, POSITIVE ELECTRODE, AND ALL-SOLID-STATE SECONDARY BATTERY

A composite positive electrode active material for an all-solid-state secondary battery containing particles of a positive electrode active material and a sulfide-based solid electrolyte layer coating surfaces of the particles, wherein the composite positive electrode active material has an average roundness that is 1.3 times or more of that of a positive electrode active material at an inner core of the composite positive electrode active material.