Method of manufacturing active material
According to an embodiment, a method of manufacturing an active material is provided. The active material includes particles of a composite oxide of the general formula Ti 1±x Nb 2±y M z O 7−δ and a carbon-including phase. Here, 0≦x≦0.15, 0≦y≦0.3, 0.01<z≦0.2, and 0<δ<0.3. M is at least one of Mg, Fe, Ni, Co, W, Ta, and Mo. The manufacturing method includes preparing a mixture by mixing in a liquid, a compound including Ti, a compound including Nb, a carbon source, and a compound including an element M, obtaining a precursor from the mixture, and calcining the precursor. The calcination is performed in a mixed atmosphere including nitrogen and oxygen, or argon and oxygen, with an oxygen concentration of 5% to 15%.
1. A method of manufacturing an active material including particles of a composite oxide represented by a general formula Ti 1±x Nb 2±y M z O 7-δ (M is at least one element selected from the group consisting of Mg, Fe, Ni, Co, W, Ta, and Mo, and each subscript satisfies 0≦x≦0.15, 0≦y≦0.3, 0.01<z≦0.2, and 0<δ<0.3) and a carbon-including phase formed on the surface of the particles, the method comprising:
preparing a mixture by mixing in a liquid, a compound including Ti, a compound including Nb, a carbon source, and a compound including the element M;
obtaining a precursor including Ti, Nb, M, C, and O from the mixture; and
calcining the precursor in a mixed atmosphere including nitrogen and oxygen, or argon and oxygen, where an oxygen concentration of the mixed atmosphere is 5% to 15%.
2. The method of manufacturing an active material according to claim 1 , wherein the liquid includes water, alcohol, or a mixture of water and alcohol.
3. The method of manufacturing an active material according to claim 1 , wherein the precursor is obtained by adjusting a pH of the mixture to alkaline pH, taking out from the liquid a precipitate formed as a result of adjusting the pH of the mixture, and drying the precipitate.
4. The method of manufacturing an active material according to claim 1 , wherein the precursor is obtained by gelling the mixture and heating a resulting gel-form compound at a temperature of from 300° C. to 500° C.
5. The method of manufacturing an active material according to claim 1 , wherein the mixture is obtained by mixing the compound including Ti, the compound including Nb, the carbon source, the compound including an element M, and water in an autoclave, and the precursor is obtained by heating the mixture in the autoclave at a temperature of from 110° C. to 240° C.
6. The method of manufacturing an active material according to claim 1 , wherein the calcination temperature of the precursor is in a range of from 800° C. to 1000° C.
7. A method of manufacturing an active material according to claim 1 , wherein the carbon source is an organic compound including a COOA group, wherein A is selected from the group consisting of H, Li, and Na.
8. The method of manufacturing an active material according to claim 1 , wherein the carbon source is carbon black.
9. The method of manufacturing an active material according to claim 1 , wherein the compound including an element M is selected from the group consisting of acetate, nitrate, sulfate, chloride, oxide, and hydroxide of the element M.
10. The method of manufacturing an active material according to claim 1 , wherein the element M is Fe.
11. The method of manufacturing an active material according to claim 1 , wherein the element M is Mo or Ta.
12. The method of manufacturing an active material according to claim 1 , wherein the active material is an active material for batteries.