Lithium-Iron Disulfide Cell Design

Abstract

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.

What is claimed: 
     
         1 . An FR6 electrochemical cell comprising:
 an R6 sized container having an external height no greater than about 50.5 mm and an external diameter no greater than about 14.5 mm;   a jellyroll electrode assembly having less than 200 cm 2  of interfacial area between an anode consisting essentially of lithium or lithium-based alloy with a thickness greater than 200 microns and a cathode comprising a mix coated onto a metallic foil current collector, wherein the mix has at least 91 wt. % pyrite and a final solids packing between 58% to 70%;   an electrolyte consisting essentially of one or more electrolytic salts dissociated in one or more solvents comprising at least 50 vol. % of one or more ethers based on total volume of the solvents, said one or more solvents not including any carbonate-based solvents; and   wherein the cell experiences a comparative drop of R10 resistance in excess of 20% at about 66% depth of discharge during the Digital Still Camera Test.   
     
     
         2 . The electrochemical cell according to  claim 1 , wherein the cell has an energy per unit of interfacial area in excess of 21 mWh/cm 2  on the Digital Still Camera Test. 
     
     
         3 . The electrochemical cell according to  claim 1 , wherein the cell has an energy per unit of interfacial area in excess of 23 mWh/cm 2  on the Digital Still Camera Test. 
     
     
         4 . The electrochemical cell according to  claim 1 , wherein the cell has an energy per unit of interfacial area in excess of 27 mWh/cm 2  on the Digital Still Camera Test. 
     
     
         5 . The electrochemical cell according to  claim 1 , wherein the interfacial area is less than 185 cm 2 . 
     
     
         6 . The electrochemical cell according to  claim 1 , wherein the interfacial area is less than 175 cm 2 . 
     
     
         7 . The electrochemical cell according to  claim 1 , wherein the mix has at least 93 wt. % of pyrite. 
     
     
         8 . The electrochemical cell according to  claim 1 , wherein the mix has at least 96 wt. % of pyrite. 
     
     
         9 . The electrochemical cell according to  claim 1 , wherein the solvents comprise greater than 90 vol. % of one or more ethers. 
     
     
         10 . The electrochemical cell according to  claim 1 , wherein the electrolytic salt, when dissociated in the one or more solvents, includes I − . 
     
     
         11 . An electrochemical cell according to  claim 1 , wherein the drop of R10 resistance is in excess of 30%. 
     
     
         12 . An electrochemical cell according to  claim 1 , wherein the drop of R10 resistance is in excess of 45%. 
     
     
         13 . An electrochemical cell according to  claim 1 , wherein the thickness of lithium is at least 225 microns. 
     
     
         14 . An electrochemical cell according to  claim 1 , wherein the thickness of the lithium is at least 250 microns. 
     
     
         15 . 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 1.00. 
     
     
         16 . An electrochemical cell according to  claim 1 , wherein the jellyroll electrode assembly has a ratio that is less than or equal to 0.90. 
     
     
         17 . An electrochemical cell according to  claim 1 , wherein the jellyroll electrode assembly has a ratio that is less than or equal to 0.85.