Electrolyte Additive for Non-Aqueous Electrochemical Cells

Abstract

An electrochemical secondary cell is disclosed. The cell includes a cathode, an anode, a current collector including aluminum, and an electrolyte containing a perchlorate salt and a second salt. The electrolyte is essentially free of LiPF 6 .

1 - 47 . (canceled) 
     
     
         48 . A method of making a lithium electrochemical cell in which the corrosion of a current collector comprising aluminum is suppressed, the method comprising
 including a sufficient quantity of a perchlorate salt in an electrolyte including at least one lithium salt other than lithium perchlorate to shift corrosion potential of an aluminum electrode by at least 125 mV when tested by continuous cyclic voltammetry in an electrochemical glass cell having an aluminum working electrode, a lithium reference electrode, and two lithium auxiliary electrodes, the continuous cyclic voltammetry including cycles in which the potential initially is set to an open circuit potential, then anodically scanned to +4.5 V, and then reversed to an open circuit potential, the scan rate being 50 mV/sec, the corrosion potential being the potential at which anodic current density reached 10 −5  A/cm 2  at a first cycle; and   incorporating the electrolyte into a lithium electrochemical cell having an anode, a cathode, and a cathode current collector comprising aluminum.   
     
     
         49 . The method of  claim 48 , wherein a sufficient quantity of the perchlorate salt is included in the electrolyte to shift the corrosion potential of the aluminum electrode by at least 300 mV. 
     
     
         50 . The method of  claim 48 , wherein the perchlorate salt is lithium perchlorate. 
     
     
         51 . The method of  claim 48 , wherein at least 500 ppm of the perchlorate salt is included in the electrolyte. 
     
     
         52 . The method of  claim 48 , wherein at least 2,500 ppm of the perchlorate salt is included in the electrolyte. 
     
     
         53 . The method of  claim 48 , wherein less than 20,000 ppm of the perchlorate salt is included in the electrolyte. 
     
     
         54 . The method of  claim 48 , wherein the electrolyte does not include LiPF 6 . 
     
     
         55 . The method of  claim 48 , wherein the electrolyte comprises LiTFS, LiTFSI, or a combination of LiTFS and LiTFSI. 
     
     
         56 . The method of  claim 48 , wherein the cathode includes manganese dioxide. 
     
     
         57 . The method of  claim 48 , wherein the cathode includes iron disulfide. 
     
     
         58 . The method of  claim 48 , wherein the cathode current collector comprises an aluminum alloy. 
     
     
         59 . The method of  claim 58 , wherein the cell further includes a positive lead comprising an aluminum alloy different from the aluminum alloy used in the cathode current collector, and wherein the cathode current collector is coupled to the positive lead. 
     
     
         60 . The method of  claim 48 , wherein the electrochemical cell further includes a positive tab comprising stainless steel coupled to the cathode current collector. 
     
     
         61 . The method of  claim 48 , wherein the electrolyte includes less than 1 ppm of aluminum and 1 ppm of iron in the electrolyte if the cathode and positive tab are aged in the electrolyte for 20 days at 60°. 
     
     
         62 . The method of  claim 48 , wherein a sufficient quantity of the perchlorate salt is included in the electrolyte to shift the potential of the aluminum electrode at least 600 mV. 
     
     
         63 . The method of  claim 48 , wherein the electrochemical cell further includes a positive tab coupled to the cathode current collector, and wherein the electrolyte includes less than 1 ppm of aluminum in the electrolyte if the cathode and positive tab are aged in the electrolyte for 20 days at 60°. 
     
     
         64 . The method of  claim 48 , wherein the electrochemical cell further includes a positive tab comprising nickel coupled to the cathode current collector. 
     
     
         65 . The method of  claim 64 , wherein the electrolyte includes less than 1 ppm of aluminum and 1 ppm of nickel if the cathode and positive tab are aged in the electrode for 20 days at 60° C.