METHOD FOR FORMING POSITIVE ELECTRODE ACTIVE MATERIAL

A method for forming a positive electrode active material of a lithium ion secondary battery is provided. The method for forming a positive electrode active material includes a first step of placing a first container in which a mixture of a lithium oxide, a fluoride, and a magnesium compound are put, in a heating furnace, a second step of providing an atmosphere including oxygen in an inside of the heating furnace, and a third step of heating the inside of the heating furnace. The third step is performed after the first step and the second step are performed. Preferably, an atmosphere including oxygen is provided in the heating furnace before the inside of the heating furnace is heated. More preferably, the fluoride is lithium fluoride and the magnesium compound is magnesium fluoride.