Non-Aqueous Electrolytic Solution With Mixed Salts

Abstract

The use of at least two electrolyte salts in a lithium secondary battery provides improved battery performance such as long cycle life of high discharge capacity and high capacity retention.

1 - 39 . (canceled)  
     
     
         40 . A non-aqueous electrolytic solution comprising: 
 a. a non-aqueous solvent, wherein the non-aqueous solvent comprises ethylene carbonate and ethylmethyl carbonate in a volume ratio of about 1:4 to about 1:1,    b. a first salt comprising lithium bis(oxalato)borate in a concentration of greater than 0.15 M to about 2.0 M and    c. a second salt in a concentration of about 0.1 M to about 1.6 M, wherein the second salt is selected from the group consisting of LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , LiTaF 6 , LiAlCl 4 , Li 2 B 10 , LiCF 3 SO 3 , LiE(C n F 2n+1 SO 2 ) m , wherein m=2 or 3, wherein E=N when m=2, and wherein E=C when m=3, and n=1-10; LiPF x (R F ) 6−x , and LiBF y (R F ) 4−y , wherein R F  represents perfluorinated C 1 -C 20  alkyl groups or perfluorinated aromatic groups, x=0-5, and y=0-3, and combinations thereof.    
     
     
         41 . The non-aqueous electrolytic solution of  claim 40 , wherein the second salt is selected from the group consisting of LiPF 6 , LiBF 4 , and combinations thereof.  
     
     
         42 . The non-aqueous electrolytic solution of  claim 40 , wherein lithium bis(oxalato)borate is present in a concentration of greater than 0.15 M to about 1.0 M.  
     
     
         43 . The non-aqueous electrolytic solution of  claim 40 , wherein lithium bis(oxalato)borate is present in a concentration of about 0.4 M to about 0.8 M.  
     
     
         44 . A non-aqueous electrolytic solution comprising: 
 a. a non-aqueous solvent,    b. a first salt comprising lithium bis(oxalato)borate in a concentration of greater than 0.15 M to about 2.0 M and    c. a second salt in a concentration of about 0.1 M to about 1.6 M, wherein the second salt is selected from the group consisting of LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , LiTaF 6 , LiAlC 4 , Li 2 B 10 Cl 10 , LiCF 3 SO 3 , LiE(C n F 2n+1 SO 2 ) m , wherein m=2 or 3, wherein E=N when m=2, and wherein E=C when m=3, and n=1-10; LiPF x (R F ) 6−x , and LiBF y (R F ) 4−y , wherein R F  represents perfluorinated C 1 -C 20  alkyl groups or perfluorinated aromatic groups, x=0-5, and y=0-3, and combinations thereof.    
     
     
         45 . The non-aqueous electrolytic solution of  claim 44 , wherein the non-aqueous solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl methyl carbonate and combinations thereof.  
     
     
         46 . A non-aqueous electrolytic solution comprising: 
 a. a non-aqueous solvent selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, tetrahydrofuran, 2-methyl tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, acetonitrile, dimethylformamide, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, γ-butyrolactone, 2methyl-γ-butyrolactone, 3-methyl-γ-butyrolactone, 4-methyl-γ-butyrolactone, β-propiolactone, δ-valerolactone, trimethyl phosphate, triethyl phosphate, tris(2-chloroethyl) phosphate, tris(2,2,2-trifluoroethyl) phosphate, tripropyl phosphate, triisopropyl phosphate, tributyl phosphate, trihexyl phosphate, triphenyl phosphate, tritolyl phosphate, and combinations thereof.    b. a first salt comprising lithium bis(oxalato)borate in a concentration of greater than 0.15 M to about 2.0 M and    c. a second salt in a concentration of about 0.01 M to about 2.5 M, wherein the second salt is selected from the group consisting of LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , LiTaF 6 , LiAlCl 4 , Li 2 B 10 Cl 10 , LiCF 3 SO 3 , LiE(C n F 2n+1 SO 2 ) m , wherein m=2 or 3, wherein E=N when m=2, and wherein E=C when m=3, and n=1-10; LiPF x (R F ) 6−x , and LiBF y (R F ) 4−y , wherein R F  represents perfluorinated C 1 -C 20  alkyl groups or perfluorinated aromatic groups, x=0-5, and y=0-3, and combinations thereof.