Abstract: Provided is a novel compound which can be used for positive-electrode catalysts of metal-air batteries. The melilite-type complex oxide according to the present invention is represented by a general formula (BazSr1?z)2CoxFe2?2x(SiyGe1?y)1+xO7 (in the formula, 0?x?1, 0?y?1, and 0?z?1, excluding the case where x=1, y=1, and z=0, the case where x=1, y=1, and z=1, the case where x=1, y=0, and z=0, the case where x=1, y=0, and z=1, the case where x=0, y=0, and z=0, and the case where x=0, y=0, and z=1).

Abstract: Provided is a metal oxide containing a brownmillerite-type manganese oxide represented by (Ca2-xAx)(MnyAlzE2-y-z)wO5+? (in the formula, A represents one or more alkaline earth metal elements other than Ca; E represents one or more 3d transition metal elements or earth metal elements other than Mn and Al; and x, y, z, ?, and w satisfy 0?x?2, 0<y?2, 0?z<2, 0<y+z?2, 0???0.5, and 0.8?w?1.2), wherein the metal oxide has a defect in a (020) plane of a crystal of the brownmillerite-type manganese oxide.

Abstract: Provided is a novel compound which can be used for positive-electrode catalysts of metal-air batteries. The melilite-type complex oxide according to the present invention is represented by a general formula (BazSr1?z)2CoxFe2?2x(SiyGe1?y)1+xO7 (in the formula, 0?x?1, 0?y?1, and 0?z?1, excluding the case where x=1, y=1, and z=0, the case where x=1, y=1, and z=1, the case where x=1, y=0, and z=0, the case where x=1, =0, and z=1, the case where x=0, y=0, and z=0, and the case where x=0, y=0, and z=1).

Abstract: Provided is a positive-electrode catalyst which has excellent durability and excellent activity in the environment in which a metal-air battery is operated. The positive-electrode catalyst for a metal-air battery according to the present invention includes a melilite-type complex oxide represented by a general formula (BazSr1?z)2CoxFe2?2x(SiyGe1?y)1?xO7 (in the formula, 0?x?1, 0?y?1, and 0?z?1).

Abstract: A novel transition metal oxide catalyst that is equivalent to precious metal catalysts, and an air electrode and an air secondary battery using this catalyst are provided. The catalyst is a catalyst for an air electrode including a brownmillerite-type transition metal oxide and represented by General Formula (1) below: A2B1B2O5??(1) where A represents Ca, Sr, Ba, or a rare earth element(RE), B1 is a metal atom that forms a tetrahedral structure together with oxygen atoms, and B2 is a metal atom that forms an octahedral structure together with oxygen atoms. Disclosed are an air electrode for a metal-air secondary battery that includes the catalyst, and a metal-air secondary battery that includes an air electrode including the catalyst, a negative electrode including a negative electrode active material, and an electrolyte intervening between the air electrode and the negative electrode.

Abstract: A novel transition metal oxide catalyst that is equivalent to precious metal catalysts, and an air electrode and an air secondary battery using this catalyst are provided. The catalyst is a catalyst for an air electrode including a brownmillerite-type transition metal oxide and represented by General Formula (1) below: A2B1B2O5??(1) where A represents Ca, Sr, Ba, or a rare earth element(RE), B1 is a metal atom that forms a tetrahedral structure together with oxygen atoms, and B2 is a metal atom that forms an octahedral structure together with oxygen atoms. Disclosed are an air electrode for a metal-air secondary battery that includes the catalyst, and a metal-air secondary battery that includes an air electrode including the catalyst, a negative electrode including a negative electrode active material, and an electrolyte intervening between the air electrode and the negative electrode.

Abstract: An oxygen excess type metal oxide expressed with the following formula (1) and exhibiting high speed reversible oxygen diffusibility whereby a large amount of excess oxygen is diffused at a high speed and reversibly in a low temperature region: AjBkCmDnO7+???(1) where A: one or more trivalent rare earth ions and Ca B: one or more alkaline earth metals C, D: one or more oxygen tetra-coordinated cations among which at least one is a transition metal, where j>0, k>0, and, independently, m?0, n?0, and j+k+m+n=6, and 0<??1.5.