| abstract |
Provided is an active material for a fluoride-ion secondary battery, the active material containing a composite fluoride. The composite fluoride has a layered structure and is represented by a composition formula A m M n F x , where A is an alkali metal, M is a transition metal, 0 < m ≤ 2, 1 ≤ n ≤ 2, and 3 ≤ x ≤ 4. The alkali metal may be at least one kind selected from the group consisting of Na, K, Rb, and Cs. The transition metal may be a 3d transition metal. |