| abstract |
A sodium secondary battery having excellent cycle characteristics and excellent discharge characteristics at a large current density is provided. A transition metal chalcogen compound represented by the following formula (I), which includes a first electrode, a second electrode, and a non-aqueous electrolyte, and in which the first electrode can dope and dedope sodium ions, is provided. Or as a main component, and the non-aqueous electrolyte contains a chain carbonate. MZ 2 (I) (Here, M represents one or more transition metal elements selected from the group consisting of Group 4 elements and Group 5 elements in the IUPAC periodic table, and Z represents one type selected from the group consisting of S, Se and Te. (The above chalcogen elements are represented.) [Selection figure] None |