| 摘要 |
Disclosed are: a composite metal oxide; a positive electrode active material; a positive electrode; and a sodium secondary battery. The composite metal oxide has an a-NaFeO2-type crystal structure, has a spacing between faces (104) of not less than 2.16 angstroms and less than 2.18 angstroms, and is represented by formula (1): Na(FexNiyMn1-x-y)O2 (wherein x represents a numeral value of 0.1 to 0.6 inclusive; and y represents a numeral value of 0 to 0.9 exclusive). The positive electrode active material comprises the composite metal oxide. The positive electrode comprises the positive electrode active material. The sodium secondary battery involves the positive electrode. |
