Electrochemical cells with improved separator and electrolyte

Abstract

An electrochemical cell is described. The electrochemical cell includes an anode, a cathode, a separator between said anode and said cathode, and an electrolyte. The electrolyte includes a salt dissolved in an organic solvent. The separator in combination with the electrolyte has an area specific resistance less than 2 ohm-cm 2 . The electrochemical cell has an interfacial anode to cathode ratio of less than about 1.1.

What is claimed is: 
     
         1 . An electrochemical cell comprising an anode, a cathode, a separator between said anode and said cathode, and an electrolyte, said electrolyte comprising a salt dissolved in an organic solvent, and said separator in combination with said electrolyte has an area specific resistance less than 2 ohm-cm 2 , and said electrochemical cell has an interfacial anode to cathode ratio of less than about 1.2. 
     
     
         2 . The electrochemical cell of  claim 1  wherein the separator has a pore size between about 0.005 to about 5 micron. 
     
     
         3 . The electrochemical cell of  claim 1  wherein the separator has a tortuosity less than about 2.5. 
     
     
         4 . The electrochemical cell of  claim 1  wherein the separator has a porosity between about 30% and about 70%. 
     
     
         5 . The electrochemical cell of  claim 1  wherein the electrolyte comprises a plurality of salts dissolved in an organic solvent. 
     
     
         6 . The electrochemical cell of  claim 1  wherein the organic solvent comprises an ether-based solvent. 
     
     
         7 . The electrochemical cell of  claim 6  wherein the ether-based solvent is selected from the group consisting of dimethoxyethane, ethyl glyme, diglyme, dimethoxypropane, triglyme, and dioxolane. 
     
     
         8 . The electrochemical cell of  claim 1  further comprising at least one co-solvent included in the electrolyte solvent. 
     
     
         9 . The electrochemical cell of  claim 8  wherein the co-solvent is present in an amount less than 25 weight percent based on the weight of the solvent of the electrolyte solution and wherein the co-solvent is selected from the group consisting of 3,5-dimethylisoxazole, 3-methyl-2-oxazolidone, propylene carbonate, ethylene carbonate, butylene carbonate and sulfolane. 
     
     
         10 . The electrochemical cell of  claim 1  wherein the anode is selected from the group consisting of carbon and graphite. 
     
     
         11 . The electrochemical cell of  claim 1  wherein the separator is wetted by the electrolyte. 
     
     
         12 . The electrochemical cell of  claim 1  wherein the interfacial anode to cathode ratio is between about 0.80 and about 1.05. 
     
     
         13 . The electrochemical cell of claim  18  wherein the interfacial anode to cathode ratio is between about 0.90 and about 1.0. 
     
     
         14 . The electrochemical cell of  claim 1  wherein the separator has a thickness from about 8 to about 30 micrometers. 
     
     
         15 . The electrochemical cell of  claim 1  wherein the cathode is selected from the group consisting of fluorinated carbon (CF x ) n  wherein x varies between about 0.5 and about 1.2 and n is greater than or equal to 1; (C 2 F) n  wherein n is greater than or equal to 1; copper sulfide (CuS); copper oxide (CuO); iron sulfide (FeS); iron disulfide (FeS 2 ); silver oxide (AgO, Ag 2 O); sulfur (S); cobalt oxide; vanadium pentoxide (V 2 O 5 ); molybdenum trioxide (MoO 3 ); molybdenum disulfide (MoS 2 ); titanium disulfide (TiS 2 ); transition metal polysulfide; lithiated metal oxide; lithiated metal sulfide; lithiated manganese oxide; Li x TiS 2 ; LiFePO 4 ; LiFeNbPO 4 ; and mixtures thereof.