Lithium-iron disulfide cell design
View Patent ↗A lithium-iron disulfide electrochemical cell design is disclosed, relying on judicious selection of the electrolyte, a thicker lithium anode and a cathode with specific characteristics selected to cooperate with the electrolyte. The resulting cell has a reduced interfacial surface area between the anode and the cathode but, surprisingly, maintains excellent high drain rate capacity.
1. An electrochemical cell comprising:
a AA-sized cylindrical container having an external height of about 50.5 mm and an external diameter of about 14.5 mm;
a jellyroll electrode assembly having: i) a separator with a thickness between 16 and 25 microns, ii) an anode consisting essentially of lithium or lithium-based alloy with a thickness of at least 225 microns, iii) a cathode comprising a mix with at least 91 wt. % pyrite coated onto a metallic foil current collector, said mix having a final solids packing between 58% to 70%, a loading of at least 28 mg of mix/cm 2 on each side of the current collector and a thickness, inclusive of the current collector and the mix coated thereon, between 220 and 500 microns, and iv) an interfacial surface area of less than 175 cm 2 ; and
an electrolyte comprising one lithium-based salt and one or more solvents, said one or more solvents consisting of at least 50 vol. % of one or more ethers based on total volume of the solvents.
2. An electrochemical cell according to claim 1 , wherein the jellyroll electrode assembly has a ratio of theoretical interfacial input capacity of the anode to the theoretical input capacity of the cathode that is between 1.00 and 0.85.
3. An electrochemical cell according to claim 1 , wherein the jellyroll electrode assembly has a ratio of theoretical interfacial input capacity of the anode to theoretical interfacial input ratio of the cathode that is less than or equal to 0.90.
4. An electrochemical cell according to claim 1 , wherein the jellyroll electrode assembly has a ratio of theoretical interfacial input capacity of the anode to theoretical interfacial input ratio of the cathode that is less than or equal to 0.85.
5. An electrochemical cell according to claim 1 , wherein the mix comprises at least 94 wt. % pyrite.
6. An electrochemical cell according to claim 1 , wherein the mix comprises at least 96 wt. % pyrite and the mix has a loading of at least 30 mg/cm 2 .
7. An electrochemical cell according to claim 1 , wherein the cell has at least one during the Digital Still Camera test selected from the group consisting of: i) a comparative drop of R10 resistance in excess of 20% at about 66% depth of discharge, and ii) an energy per unit of interfacial area in excess of 21 mWh/cm 2 .
8. An electrochemical cell according to claim 1 , wherein the cell has at least one during the Digital Still Camera test selected from the group consisting of: i) a comparative drop of R10 resistance in excess of 30% at about 66% depth of discharge, and ii) an energy per unit of interfacial area in excess of 23 mWh/cm 2 .
9. An electrochemical cell according to claim 1 , wherein the one or more solvents do not contain any carbonates and consist of greater than 90 vol. % of one or more ethers.
10. An electrochemical cell according to claim 1 , wherein the electrolyte further comprises I − dissociated in the one or more solvents.
11. An electrochemical cell according to claim 1 , wherein the thickness of the cathode is about 220 microns.
12. An electrochemical cell according to claim 1 , wherein the thickness of the cathode is between 380 and 500 microns.
13. An electrochemical cell according to claim 1 , wherein the thickness of the cathode is between 220 and 380 microns.
14. An electrochemical cell according to claim 1 , wherein the thickness of the cathode is between 220 and 380 microns.
15. An electrochemical cell comprising:
a AA-sized cylindrical container having an external height of about 50.5 mm and an external diameter of about 14.5 mm;
a jellyroll electrode assembly having: i) a separator with a thickness between 16 and 25 microns, ii) an anode consisting essentially of lithium or lithium-based alloy with a thickness greater than 200 microns, iii) a cathode comprising a mix with at least 91 wt. % pyrite coated onto a metallic foil current collector, said mix having a final solids packing between 58% to 70% and a loading of at least 28 mg of mix/cm 2 on each side of the current collector, iv) an interfacial surface area of less than 185 cm 2 , and v) a ratio of theoretical interfacial input capacity of the anode to theoretical interfacial input ratio of the cathode that is between 0.85 and 1.00; and
an electrolyte comprising one lithium-based salt and one or more solvents, said one or more solvents consisting of at least 50 vol. % of one or more ethers based on total volume of the solvents.
16. An electrochemical cell according to claim 15 , wherein the jellyroll electrode assembly has a ratio of theoretical interfacial input capacity of the anode to theoretical interfacial input ratio of the cathode that is less than or equal to 0.90.
17. An electrochemical cell according to claim 15 , wherein the mix comprises at least 94 wt. % pyrite.
18. An electrochemical cell according to claim 15 , wherein the mix comprises at least 96 wt. % pyrite and the mix has a loading of at least 30 mg/cm 2 .
19. An electrochemical cell according to claim 15 , wherein the cell has at least one during the Digital Still Camera test selected from the group consisting of: i) a comparative drop of R10 resistance in excess of 20% at about 66% depth of discharge, and ii) an energy per unit of interfacial area in excess of 21 mWh/cm 2 .
20. An electrochemical cell according to claim 15 , wherein the cell has at least one during the Digital Still Camera test selected from the group consisting of: i) a comparative drop of R10 resistance in excess of 30% at about 66% depth of discharge, and ii) an energy per unit of interfacial area in excess of 23 mWh/cm 2 .
21. An electrochemical cell according to claim 15 , wherein the one or more solvents do not contain any carbonates and consist of greater than 90 vol. % of one or more ethers.
22. An electrochemical cell according to claim 15 , wherein the electrolyte further comprises I − dissociated in the one or more solvents.