Quality for rechargeable batteries of cathode active material, and a rechargeable lithium-ion battery using it

Japanese Patent JP6200067

B2

Provided is a positive electrode active material for lithium ion secondary batteries, having a crystal structure containing a layered Li2MnO2 structure with a high theoretical electrical capacity as a basic skeleton, and having both a high theoretical electrical capacity and a high open-circuit voltage by increasing an open-circuit voltage to a value of more than 2 V by replacing a part of manganese ions with calcium ions by adding the calcium ions. That is, a positive electrode active material for secondary batteries mainly containing a compound represented by a chemical composition formula Li2−xMn1−yCayO2, and an electrode and a battery including the same are realized. In the formula, x satisfies 0