The use of the fluoride ion conductive material of the embodiment is not limited. The material can be used, for example, as a solid fluoride ion conductive material. More specifically, the material can be used as a solid electrolyte conducting fluoride ions. The ion conductive material of the embodiment can be used in, for example, a fluoride ion secondary battery. The fluoride ion secondary battery is a rechargeable secondary battery. The fluoride ion secondary battery is charged and discharged by migration of fluoride ions between the positive electrode and the negative electrode via an electrolyte. The fluoride ion conductive material of the embodiment can be used as an electrolyte included in at least one layer selected from the positive electrode layer, the negative electrode layer, and the electrolyte layer of the battery. More specifically, the fluoride ion conductive material of the embodiment can be used as an electrolyte included in the electrolyte layer, in particular, a solid electrolyte layer, of the battery. The fluoride ion conductive material of the embodiment can also be used as the negative electrode active material included in the negative electrode layer of a fluoride ion secondary battery depending on the combination with the positive electrode active material included in the positive electrode layer.

A fluoride ion secondary battery including the fluoride ion conductive material of the embodiment can be an all-solid secondary battery. The all-solid secondary battery is highly safe and can have a high energy density depending on the structure of the positive electrode layer, the electrolyte layer, and the negative electrode layer.