Lithium-sulphur cell
The present invention relates to a lithium-sulphur cell comprising an anode comprising lithium metal or lithium metal alloy;a cathode comprising a mixture of electroactive sulphur material and solid electroconductive material; and a liquid electrolyte comprising at least one lithium salt and a solvent comprising a dinitrile.
1. A lithium-sulphur cell comprising:
an anode comprising lithium metal or lithium metal alloy;
a cathode comprising a mixture of electroactive sulphur material and solid electroconductive material. wherein the electroactive sulphur material is reduced to polysulfide species and/or lithium sufide during discharge of the lithium-sulphur cell, and wherein the solid electroconductive material consists essentially of carbon black, carbon fiber, carbon nanotubes, or mixtures thereof; and
a liquid electrolyte composition comprising at least one lithium salt, lithium polysulphides, and a dintrile;
wherein the dinitrile has the formula (II):
wherein:
p is 0 or 1,
q is an integer of 1 to 9,
r is 0 or 1, and
R 3 , R 4 , R 5 and R 6 are each independently selected from H and a C 1 to C 6 alkyl group, and wherein at least one of R 3 and R 4 is H and at least one of R 5 and R 6 is H; and
wherein the concentration of lithium salt in the liquid electrolyte composition is 0.2 M to 3M.
2. The cell of claim 1 , wherein at least one of R 3 , R 4 , R 5 and R 6 is a C 1 to C 6 alkyl group.
3. The cell of claim 1 , wherein p is 0 and r is 1.
4. The cell of claim 3 , wherein q is 2.
5. The cell of claim 3 , wherein at least one of R 5 and R 6 is H and the other is a C 1 to C 6 alkyl.
6. The cell of claim 1 , wherein the C 1 to C 6 alkyl group is methyl.
7. The cell of claim 1 , wherein the dinitrile is selected from at least one of 2-methylglutaronitrile, succinonitrile and adiponitrile.
8. The cell of claim 1 , wherein the electroactive sulphur material comprises elemental sulphur.
9. The cell of claim 1 , wherein the solid electroconductive material comprises carbon.
10. The cell of claim 1 , wherein the solid electroconductive material consists essentially of carbon black, carbon fiber, or carbon nanotubes.
11. The cell of claim 1 , wherein the solid electroconductive material consists essentially of carbon black.
12. The cell of claim 1 , wherein the solid electroconductive material consists of carbon black, carbon fiber, or carbon nanotubes.
13. The cell of claim 1 , wherein the solid electroconductive material consists of carbon black.
14. The cell of claim 1 , wherein the concentration of lithium salt in the liquid electrolyte composition is 0.4 M to 2M.
15. The cell of claim 1 , wherein the concentration of lithium salt in the liquid electrolyte composition is 0.5 M to 1M.
16. The lithium-sulphur cell of claim 1 , wherein the electroactive sulphur material comprises elemental sulphur or a sulphur-based inorganic compound that is reduced to polysulfide species and/or lithium sufide during discharge of the lithium-sulphur cell.