Lithium-iron disulfide cell design
View Patent ↗The invention relates to electrochemical cells having a jellyroll electrode assembly that includes a lithium-based negative electrode, a positive electrode with a coating comprising greater than about 94 wt. % of iron disulfide.
1. A method of making a lithium-FeS 2 battery with at least 4 Wh of capacity on a 1000 mW constant power drain comprising the steps of:
a. selecting a container having a size appropriate for FR6 batteries:
b. determining an amount of FeS 2 necessary to insure that, when the cell is fully discharged, radial force of expansion is between 50% to 80% of the yield strength of the container when radial expansion forces are at a maximum during discharge of the battery under any conditions;
c. providing FeS 2 in the determined amount to a slurry mixture and coating the slurry mixture onto a metallic foil current collector and drying said coated mixture to form a cathode coating, said cathode coating having greater than 95 wt. % of FeS 2 as compared to the total weight of solids in the cathode coating;
d. forming a jellyroll electrode assembly by winding the coated current collector with a separator and an anode strip consisting essentially of lithium or a lithium alloy;
e. placing the jellyroll electrode assembly within the cylindrical container and closing the container.
2. The method of claim 1 , wherein the force of radial expansion is between 70% to 80% of the yield strength of the container when radial expansion forces are at a maximum during discharge of the battery under any conditions.
3. The method of claim 1 , further comprising deny the cathode coating to have at least one of the following: a loading of at least 24 mg/cm 2 , a void volume between 28% and 40% and a thickness, exclusive of the current collector, between 80 microns and 102 microns.
4. A method of making, a lithium-FeS 2 battery with at least 1.950 mAh of capacity on a 1000 mA constant power drain comprising the steps of:
a. selecting a container having a size appropriate for FR03 batteries;
b. determining an amount of FeS 2 necessary to insure that, when the cell is fully discharged, radial force of expansion is between 50% to 80% of the yield strength of the container when radial expansion forces are at a maximum during discharge of the battery under any conditions;
c. providing FeS 2 in the determined amount to a slurry mixture and coating the slurry mixture onto a metallic foil current collector, said slurry mixture having greater than 95 wt. % of FeS 2 as compared to the total weight of solids provided to said slurry mixture;
d. forming a jellyroll electrode assembly by winding the coated current collector with a separator and an anode strip consisting essentially of lithium or a lithium alloy;
e. placing the jellyroll electrode assembly within the cylindrical container and closing the container.
5. The method of claim 4 , wherein the force of radial expansion is between 70% to 80% of the yield strength of the container when radial expansion forces are at a maximum during discharge of the battery under any conditions.
6. The method of claim 4 , further comprising densifying the cathode coating to have at least one of the following: a loading of at least 24 mg/cm 2 , a void volume between 28% and 40% and a thickness, exclusive of the current collector, between 80 microns and 102 microns.