Non-aqueous electrolytic solution and lithium secondary battery

Abstract

A non-aqueous electrolytic solution favorably employable for a lithium secondary battery employs a non-aqueous electrolytic solution which comprises a non-aqueous solvent and an electrolyte which further contains 0.001 to 0.8 weight % of a biphenyl derivative having the formula: in which each of Y 1 and Y 2 represents hydroxyl, alkoxy, hydrocarbyl, hydrogen, acyloxy, alkoxycarbonyloxy, alkylsulfonyloxy, or halogen, and each of p and q is an integer of 1 to 3.

What is claimed is:  
     
         1 . A non-aqueous electrolytic solution which comprises a non-aqueous solvent and an electrolyte which further contains 0.001 to 0.8 weight % of a biphenyl derivative having the following formula:  
       
         
           
           
               
               
           
         
       
       in which each of Y 1  and Y 2  independently represents a hydroxyl group, an alkoxy group, a hydrocarbyl group, a hydrogen atom, an acyloxy group, an alkoxycarbonyloxy group, an alkylsulfonyloxy group or a halogen atom, and each of p and q independently is an integer of 1 to 3.  
     
     
         2 . The non-aqueous electrolytic solution of  claim 1 , wherein the biphenyl derivative has the following formula:  
       
         
           
           
               
               
           
         
       
       in which Y represents a hydroxyl group, an alkoxy group, a hydrocarbyl group, a hydrogen atom, an acyloxy group, an alkoxycarbonyloxy group, or an alkylsulfonyloxy group.  
     
     
         3 . The non-aqueous electrolytic solution of  claim 1 , wherein the amount of the biphenyl derivative is in the range of 0.01 to 0.5 weight %.  
     
     
         4 . The non-aqueous electrolytic solution of  claim 2 , wherein the amount of the biphenyl derivative is in the range of 0.01 to 0.5 weight %.  
     
     
         5 . The non-aqueous electrolytic solution of  claim 1 , wherein the non-aqueous solvent comprises a combination of a cyclic carbonate and a linear chain carbonate.  
     
     
         6 . The non-aqueous electrolytic solution of  claim 2 , wherein the non-aqueous solvent comprises a combination of a cyclic carbonate and a linear chain carbonate  
     
     
         7 . The non-aqueous electrolytic solution of  claim 1 , wherein the non-aqueous solvent comprises a high dielectric constant solvent which is selected from the group consisting of ethylene carbonate, propylene carbonate, and butylene carbonate, and a low viscosity solvent which is selected from the group consisting of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-diode, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, γ-butyrolactone, acetonitrile, methyl propionate, and dimethylformamide.  
     
     
         8 . The non-aqueous electrolytic solution of  claim 2 , wherein the non-aqueous solvent comprises a high dielectric constant solvent which is selected from the group consisting of ethylene carbonate, propylene carbonate, and butylene carbonate, and a low viscosity solvent which is selected from the group consisting of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, γ-butyrolactone, acetonitrile, methyl propionate, and dimethylformamide.  
     
     
         9 . A lithium secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolytic solution which comprises a non-aqueous solvent and an electrolyte which further contains 0.001 to 0.8 weight % of a biphenyl derivative having the following formula:  
       
         
           
           
               
               
           
         
       
       in which each of Y 1  and Y 2  independently represents a hydroxyl group, an alkoxy group, a hydrocarbyl group, a hydrogen atom, an acyloxy group, an alkoxycarbonyloxy group, an alkylsulfonyloxy group or a halogen atom, and each of p and q independently is an integer of 1 to 3.  
     
     
         10 . The lithium secondary battery of  claim 9 , wherein the biphenyl derivative in the non-aqueous electrolytic solution has the following formula:  
       
         
           
           
               
               
           
         
       
       in which Y represents a hydroxyl group, an alkoxy group, a hydrocarbyl group, a hydrogen atom, an acyloxy group, an alkoxycarbonyloxy group, or an alkylsulfonyloxy group.