Secondary battery, battery pack, vehicle, and stationary power supply
According to one embodiment, a secondary battery is provided. The secondary battery includes a positive electrode, a negative electrode including titanium oxide particles, and an aqueous electrolyte. The surfaces of the titanium oxide particles are partially covered with an alkyl-based silane compound. The ratio I B /I A of the intensity I B of the second peak P B to the intensity I A of the first peak P A is within a range of 4 to 10. The first peak P A is a maximum peak present within a range of 3200 cm −1 to 3600 cm −1 in an infrared absorption spectrum of the titanium oxide particles. The second peak P B is a maximum peak present within a range of 565 cm −1 to 570 cm −1 in the infrared absorption spectrum of the titanium oxide particles.
1. A secondary battery comprising: a positive electrode; a negative electrode comprising titanium oxide particles; and an aqueous electrolyte, wherein
surfaces of the titanium oxide particles are partially covered with an alkyl-based silane compound comprising at least one selected from the group consisting of methyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, trimethoxy (3,3,3-trifluoropropyl) silane, dimethyldimethoxysilane, methyltriethoxysilane, and dimethyldiethoxysilane, and
a ratio I B /I A of an intensity I B of a second peak P B to an intensity I A of a first peak P A is within a range of 4 to 10, where
the first peak P A is a maximum peak present within a range of 3200 cm −1 to 3600 cm −1 in an infrared absorption spectrum of the titanium oxide particles obtained by infrared spectroscopy, and the second peak P B is a maximum peak present within a range of 565 cm −1 to 570 cm −1 in the infrared absorption spectrum.
2. The secondary battery according to claim 1 ,
wherein the infrared absorption spectrum comprises a third peak P c , which is present within a range of 2800 cm −1 to 3000 cm −1 .
3. The secondary battery according to claim 1 , wherein
the alkyl-based silane compound comprises an alkyl group, and
the alkyl group is hydrocarbon having one to 10 carbon atoms.
4. The secondary battery according to claim 1 , wherein the titanium oxide particles comprise at least one oxide selected from a group consisting of titanium dioxide, lithium titanium composite oxide, sodium titanium composite oxide, aluminum titanium composite oxide, and niobium titanium composite oxide.
5. The secondary battery according to claim 4 , wherein the titanium oxide particles comprise the titanium dioxide.
6. The secondary battery according to claim 1 , wherein the negative electrode comprises the titanium oxide particles as a negative electrode active material, and the coverages of the surfaces of the titanium oxide particles with the alkyl-based silane compound is in a range of 0.5% by mass to 1.0% by mass with respect to the total mass of the negative electrode active materials.
7. The secondary battery according to claim 1 , wherein the alkyl-based silane compound comprises at least one selected from the group consisting of a methyl group, an ethyl group, or a propyl group.
8. The secondary battery according to claim 1 , wherein surfaces of the titanium oxide particles are partially covered with at least one alkyl-based silane compound selected from the group consisting of methyltrimethoxysilane, propyltrimethoxysilane, trimethoxy(3,3,3-trifluoropropyl)silane, dimethyldimethoxysilane, methyltriethoxysilane, and dimethyldiethoxysilane.
9. The secondary battery according to claim 1 , wherein surfaces of the titanium oxide particles are partially covered with at least one alkyl-based silane compound selected from the group consisting of hexyltrimethoxysilane and decyltrimethoxysilane.
10. A battery pack comprising the secondary battery according to claim 1 .
11. The battery pack according to claim 10 , further comprising: an external power distribution terminal; and a protective circuit.
12. The battery pack according to claim 10 , comprising plural of the secondary battery, wherein the secondary batteries are electrically connected in series, in parallel, or in a combination of series connection and parallel connection.
13. A vehicle comprising the battery pack according to claim 10 .
14. A stationary power supply comprising the battery pack according to claim 10 .