Electrolyte for lithium-sulphur batteries and lithium-sulphur batteries using the same

1. An electrolyte for a lithium-sulphur battery, the electrolyte comprising a solution of at least one electrolyte salt in a mixture of aprotic solvents, the mixture of aprotic solvents consisting essentially of a eutectic mixture of sulfolane and a sulfone or a mixture of sulfolane and the sulfone that is within ±30% of the eutectic concentration of the mixture of the sulfolane and the sulfone.

2. An electrolyte as claimed in claim 1 , wherein the mixture of aprotic solvents consists essentially of a mixture of sulfolane and the sulfone that is within ±20% of the eutectic concentration of the mixture of the sulfolane and the sulfone.

3. An electrolyte as claimed in claim 1 , wherein the mixture of aprotic solvents consists essentially of a mixture of sulfolane and the sulfone that is within ±10% of the eutectic concentration of the mixture of the sulfolane and the sulfone.

4. An electrolyte as claimed in claim 1 , wherein the sulfone has a molecular weight of about 94 to 150.

5. An electrolyte as claimed in claim 1 , wherein the electrolyte salt is at least one salt or a mixture of salts selected from a group comprising: lithium hexafluorophosphate (LiPF 6 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium perchlorate (LiClO 4 ), lithium sulfonylimide trifluoromethane (LiN(CF 3 SO 2 ) 2 ) and lithium trifluorosulfonate (CF 3 SO 3 Li).

6. An electrolyte as claimed in claim 1 , wherein the concentration of the at least one electrolyte salt is between 0.1M and a saturation concentration, at operable temperature and pressure.

7. An electrolyte as claimed in claim 1 , further including as an additive one or more organic or non-organic additives for contributing to a solid electrolyte interface (SET) phase formation on a surface of a negative electrode and for improving a cycling of the negative electrode.

8. An electrolyte as claimed in claim 7 , wherein said additive is at least one substance or a mixture of substances selected from the group consisting of: S, Li 2 S n , CO 2 , SO 2 , N 2 O, Cl 2 , Br, I, and amines.

9. An electrolyte as claimed in claim 7 , wherein the amount of additive is between 0.2% and 10% of the total mass of the electrolyte.

10. An electrolyte as claimed in claim 1 , wherein the aprotic solvent is a eutectic mixture of sulfolane and ethylbutylsulfone.

11. An electrolyte as claimed in claim 1 , wherein the aprotic solvent is a eutectic mixture of sulfolane and methylpropylsulfone.

12. An electrolyte for a lithium-sulphur battery, the electrolyte comprising a solution of at least one electrolyte salt in a mixture of aprotic solvents, the mixture of aprotic solvents consisting essentially of a eutectic mixture of sulfolane and a sulfone.

13. A lithium-sulphur battery comprising a negative electrode including a lithium-containing material, a positive electrode including a sulphur-containing material and an electrolyte comprising a solution of at least one electrolyte salt in a mixture of aprotic solvents, the mixture of aprotic solvents consisting essentially of a eutectic mixture of sulfolane and a sulfone or a mixture of sulfolane and the sulfone that is within ±30% of the eutectic concentration of the mixture of the sulfolane and the sulfone.

14. A battery as claimed in claim 13 , wherein the negative electrode includes a negative electrochemically active material selected from a list comprising: metallic lithium, lithium-containing alloy, lithium combined with non-active sulphur, a compound that can reversibly intercalate lithium ions (including but not limited to metal powders, lithium metal-carbon and lithium metal-graphite intercalates and mixtures thereof), and compounds that can reversibly go through a reduction-oxidation process with lithium ions.

15. A battery as claimed in claim 13 , wherein the positive electrode includes a positive electrochemically active material comprising at least one sulphur-based material selected from a list comprising: elemental sulphur, Li 2 S n compounds (with n≧1), organic sulphur compounds, and sulphur-containing polymers.

16. A battery as claimed in claim 13 , wherein the sulfone has a molecular weight of about 94 to 150.

17. A battery as claimed in claim 13 , wherein the electrolyte salt is at least one salt or a mixture of salts selected from a group comprising: lithium hexafluorophosphate (LiPF 6 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium perchlorate (LiClO 4 ), lithium sulfonylimide trifluoromethane (LiN(CF 3 SO 2 ) 2 ) and lithium trifluorosulfonate (CF 3 SO 3 Li).

18. A battery as claimed in claim 13 , wherein the concentration of the at least one electrolyte salt is between 0.1M and a saturation concentration, at operable temperature and pressure.

19. A battery as claimed in claim 13 , further including as an additive one or more organic or non-organic additives for contributing to a solid electrolyte interface (SET) phase formation on a surface of a negative electrode and for improving a cycling of the negative electrode.

20. A battery as claimed in claim 13 , wherein the aprotic solvent is a eutectic mixture of sulfolane and ethylbutylsulfone.

21. A battery as claimed in claim 13 , wherein the aprotic solvent is a eutectic mixture of sulfolane and methylpropylsulfone.

22. A lithium-sulphur battery comprising a negative electrode including a lithium-containing material, a positive electrode including a sulphur-containing material and an electrolyte comprising a solution of at least one electrolyte salt in a mixture of aprotic solvents, the mixture of aprotic solvents consisting essentially of a eutectic mixture of sulfolane and a sulfone.