POSITIVE ELECTRODE ACTIVE MATERIAL, HIGH-TEMPERATURE OPERATION TYPE LITHIUM-ION POLYMER SECONDARY BATTERY, HIGH-TEMPERATURE OPERATION TYPE LITHIUM ION INORGANIC ALL-SOLID-STATE SECONDARY BATTERY

A positive electrode active material that is used in a high-temperature operation type lithium ion solid secondary battery, wherein the positive electrode active material is made of oxide particles, which contains a first transition element and does not include an alkali metal.