Active material, negative electrode active material, and fluoride ion secondary battery
An active material contains a composite metal fluoride containing Al, F, and Ti and can occlude and release fluoride ions. The composite metal fluoride is represented by a compositional formula: Al 1-x Ti x F y , where x satisfies 0.01≤x≤0.9 and y satisfies, 2≤y≤4.
1. An active material comprising:
a composite metal fluoride containing Al, F, and Ti, wherein
the active material is capable of occluding and releasing fluoride ions, and
the composite metal fluoride is represented by a compositional formula:
Al 1-x Ti x F y ,
where x satisfies 0.15≤x≤0.3 and y satisfies 2≤y≤4.
2. The active material according to claim 1 , wherein
the composite metal fluoride has a crystal structure; and
the Ti is located at Al site in the crystal structure.
3. A fluoride ion secondary battery comprising:
a positive electrode layer;
a negative electrode layer containing the active material according to claim 1 ; and
an electrolyte layer disposed between the positive electrode layer and the negative electrode layer.
4. The fluoride ion secondary battery according to claim 3 , wherein
the positive electrode layer contains a positive electrode active material; and
the positive electrode active material contains at least one selected from the group consisting of Co, Cu, Bi, Sn, Pb, Fe, Zn, Ga, and C.