Positive electrode active material and sodium-ion secondary battery

Abstract

Disclosed is a positive electrode active material having a P2-type structure and having a large reversible capacity. The positive electrode active material of the present disclosure comprises a Na-containing oxide. The Na-containing oxide has a P2-type structure. The Na-containing oxide at least comprises, as constituting elements, at least one element among Mn, Ni, and Co; Na; and O. An X-ray diffraction pattern of the Na-containing oxide satisfies I1/I2≤0.10. The X-ray diffraction pattern of the Na-containing oxide satisfies I1/I3≤0.70. The I1 is an X-ray diffraction peak intensity originating from (102) plane of the P2-type structure, the I2 is an X-ray diffraction peak intensity originating from (002) plane of the P2-type structure, and the I3 is an X-ray diffraction peak intensity originating from (100) plane of the P2-type structure.

Dependencies are inferred from the claim text.