A production method for producing a halide includes heat-treating, in an inert gas atmosphere, a mixed material in which LiCl and YCl.sub.3 are mixed. In the heat-treatment, the mixed material is heat-treated at higher than or equal to 200° C. and lower than or equal to 650° C.

An object of the present disclosure is to provide an all solid fluoride ion battery that has a favorable capacity property. The present disclosure achieves the object by providing an all solid fluoride ion battery comprising: a cathode layer, an anode layer, and a solid electrolyte layer formed between the cathode layer and the anode layer; wherein the anode layer includes a metal fluoride containing an M1 element, an M2 element, and a F element; the M1 element is a metal element that fluorination and defluorination occur at a potential, versus Pb/PbF.sub.2, of −2.5 V or more; the M2 element is a metal element that neither fluorination nor defluorination occur at a potential, versus Pb/PbF.sub.2, of −2.5 V or more; and the M2 element is a metal element that, when in a form of a fluoride, fluoride ion conductivity is 1×10.sup.−4 S/cm or more at 200° C.

An object of the present disclosure is to provide an all solid fluoride ion battery that has a favorable capacity property. The present disclosure achieves the object by providing an all solid fluoride ion battery comprising: a cathode layer, an anode layer, and a solid electrolyte layer formed between the cathode layer and the anode layer; wherein the anode layer includes a metal fluoride containing an M1 element, an M2 element, and a F element; the M1 element is a metal element that fluorination and defluorination occur at a potential, versus Pb/PbF.sub.2, of −2.5 V or more; the M2 element is a metal element that neither fluorination nor defluorination occur at a potential, versus Pb/PbF.sub.2, of −2.5 V or more; and the M2 element is a metal element that, when in a form of a fluoride, fluoride ion conductivity is 1×10.sup.−4 S/cm or more at 200° C.

Provided is a positive electrode material which further improves charge/discharge efficiency. The positive electrode material according to the present disclosure includes a positive electrode active material and a first solid electrolyte material. The first solid electrolyte material includes Li, M, and X, and does not include sulfur. M is at least one selected from the group consisting of metalloid elements and metal elements other than Li. X is at least one selected from the group consisting of Cl, Br, and I. The positive electrode active material includes a metal oxyfluoride.

Provided is a battery comprising a cathode, an anode, and an electrolyte layer. The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer includes a first solid electrolyte material. The second electrolyte layer includes a second solid electrolyte material which is different from the first solid electrolyte material. The first solid electrolyte material includes lithium, at least one kind selected from the group consisting of metalloid elements and metal elements other than lithium, and at least one kind selected from the group consisting of chlorine and bromine. The first solid electrolyte material does not include sulfur.

Provided is a battery in which the internal resistance is further decreased. The present disclosure provides a battery, comprising a positive electrode, a negative electrode, and an electrolyte layer provided between the positive electrode and the negative electrode. The electrolyte layer includes a first solid electrolyte material. The first solid electrolyte material includes Li, M, and X, and does not include sulfur. M is at least one selected from the group consisting of metalloid elements and metal elements other than Li. X is at least one selected from the group consisting of Cl, Br, and I. The negative electrode includes a negative electrode active material and a sulfide solid electrolyte.

Provide is a solid electrolyte material represented by a composition formula Li.sub.aY.sub.bM.sub.cX.sub.6-dF.sub.d, where M includes at least one kind selected from the group consisting of metalloid elements and metal elements other than Li and Y; X is at least one kind selected from the group consisting Cl, Br, and I; 0<a; 0<b; 0c; and 0<d<6.

Provide is a solid electrolyte material represented by a composition formula Li.sub.aY.sub.bM.sub.cX.sub.6-dF.sub.d, where M includes at least one kind selected from the group consisting of metalloid elements and metal elements other than Li and Y; X is at least one kind selected from the group consisting Cl, Br, and I; 0<a; 0<b; 0c; and 0<d<6.

Provided is a battery having further improved charging/discharging efficiency. The battery comprises a positive electrode, a negative electrode, and an electrolyte layer provided between the positive electrode and the negative electrode. The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The second electrolyte layer is provided between the first electrolyte layer and the negative electrode. The first electrolyte layer includes a first solid electrolyte material. The second electrolyte layer includes a second solid electrolyte material that is a material different from the first solid electrolyte material. The first solid electrolyte material includes Li, M, and X and does not include sulfur. M includes at least one selected from the group consisting of metalloid elements and metal elements other than Li. X is at least one selected from the group consisting of Cl, Br, and I. The reduction potential with regard to lithium of the second solid electrolyte material is lower than the reduction potential with regard to lithium of the first solid electrolyte material.

Provided is a cathode material including a cathode active material; a coating layer which coats at least a part of a surface of the cathode active material, and which includes a first solid electrolyte material; and a second solid electrolyte material. The first solid electrolyte material includes Li, M, and X; however, does not include sulfur. M includes at least one element selected from the group consisting of metalloid elements and metal elements other than Li. X includes at least one element selected from the group consisting of Cl and Br.