Secondary battery, battery pack, vehicle, and stationary power supply
According to one embodiment, there is provided a secondary battery including a positive electrode, a negative electrode, and an aqueous electrolyte. The negative electrode contains a titanium-containing oxide. The aqueous electrolyte contains a solvent and alkali metal ions or alkaline earth metal ions, the solvent containing water and a water-soluble organic solvent. An interfacial tension of the aqueous electrolyte is 37 mN/m or less.
1. A secondary battery comprising:
a positive electrode;
a negative electrode comprising a titanium-containing oxide; and
an aqueous electrolyte comprising a solvent and alkali metal ions or alkaline earth metal ions, the solvent comprising water and a water-soluble organic solvent, and an interfacial tension of the aqueous electrolyte being 37 mN/m or less.
2. The secondary battery according to claim 1 , wherein the interfacial tension of the aqueous electrolyte is 34 mN/m or less.
3. The secondary battery according to claim 1 , wherein the aqueous electrolyte further comprises a first compound, the first compound comprising an organic compound, the organic compound comprising a hydrophilic portion and a hydrophobic portion.
4. The secondary battery according to claim 3 , wherein the organic compound is a nonionic surfactant.
5. The secondary battery according to claim 4 , wherein the nonionic surfactant comprises one or more surfactant selected from a group consisting of polyoxyethylene alkyl ether and polyoxyalkylene alkyl ether.
6. The secondary battery according to claim 4 , wherein the nonionic surfactant has a molecular weight within a range of from 200 to 4000.
7. The secondary battery according to claim 1 , wherein the aqueous electrolyte is a first aqueous electrolyte in contact with the negative electrode.
8. The secondary battery according to claim 7 , wherein pH of the first aqueous electrolyte is 7 or more.
9. The secondary battery according to claim 1 , wherein the water-soluble organic solvent includes at least one solvent selected from a group consisting of N-methyl-2-pyrrolidone, methanol, ethanol, propanol, isopropanol, butanol, isobutyl alcohol, sec-butyl alcohol, tert-butanol, ethylene glycol, 1,2-dimethoxyethane, tetrahydrofuran, 1,4-dioxane, acetone, ethyl methyl ketone, acetonitrile, dimethylformamide, hexamethylphosphoric triamide, triethylamine, pyridine, and dimethyl sulfoxide.
10. The secondary battery according to claim 1 , wherein the negative electrode further comprises zinc.
11. The secondary battery according to claim 1 , wherein the negative electrode further comprises a negative electrode current collector comprising zinc.
12. A battery pack comprising the secondary battery according to claim 1 .
13. The battery pack according to claim 12 , further comprising an external power distribution terminal and a protective circuit.
14. The battery pack according to claim 12 , further comprising plural of the secondary battery,
wherein the secondary batteries are electrically connected in series, in parallel, or in combination of in-series connection and in-parallel connection.
15. A vehicle comprising the battery pack according to claim 12 .
16. The vehicle according to claim 15 , which comprises a mechanism configured to convert kinetic energy of the vehicle into regenerative energy.
17. A stationary power supply comprising the battery pack according to claim 12 .