Nonaqueous electrolytic secondary battery and method of making the same

Abstract

A nonaqueous electrolytic secondary battery includes a negative electrode, a positive electrode, and a nonaqueous electrolytic solution including an electrolytic salt dissolved in a nonaqueous solvent. A polymer is added to the nonaqueous electrolytic solution. Also, a method of making a nonaqueous electrolytic secondary battery includes the steps of placing a negative electrode, a positive electrode, and a nonaqueous electrolytic solution including an electrolytic salt dissolved in a nonaqueous solvent, in a battery housing to assemble a battery; and charging and discharging the battery under overcharge conditions or applying a pulse voltage to the battery.

What is claimed is:  
     
         1 . A nonaqueous electrolytic secondary battery comprising: 
 a negative electrode;    a positive electrode; and    a nonaqueous electrolytic solution comprising an electrolytic salt dissolved in a nonaqueous solvent;    wherein a polymer is added to said nonaqueous electrolytic solution.    
     
     
         2 . A nonaqueous electrolytic secondary battery according to  claim 1 , wherein said polymer has a molecular weight ranging from 500 to 500,000.  
     
     
         3 . A nonaqueous electrolytic secondary battery according to  claim 1 , wherein said polymer is an oxygen-containing polymer.  
     
     
         4 . A nonaqueous electrolytic secondary battery according to  claim 3 , wherein said polymer has at least one of a carbonyl group and an ether group.  
     
     
         5 . A nonaqueous electrolytic secondary battery according to  claim 4 , wherein said polymer is represented by any one of the following general formulae:  
       R 1 —COO—R 2  k    
       where R 1  and R 2  are hydrocarbon groups;  
       R 3 —COO—R 4 —OCO—R 5  m    
       where R 3 , R 4 , and R 5  are hydrocarbon groups;  
       R 6 —COO—R 7 —CO—R 8  n    
       where R 6 , R 7 , and R 8  are hydrocarbon groups; and  
       R 9 —COO—R 10 —O—R 11  g    
       where R 9 , R 10 , and R 11  are hydrocarbon groups.  
     
     
         6 . A nonaqueous electrolytic secondary battery according to  claim 1 , wherein said negative electrode comprises a carbonaceous material.  
     
     
         7 . A nonaqueous electrolytic secondary battery according to  claim 1 , wherein said positive electrode comprises a lithium-transition metal double oxide.  
     
     
         8 . A nonaqueous electrolytic secondary battery according to  claim 1 , wherein the nonaqueous solvent of said nonaqueous electrolytic solution comprises a carbonate-based solvent.  
     
     
         9 . A nonaqueous electrolytic secondary battery according to  claim 1 , wherein the electrolytic salt of said nonaqueous electrolytic solution is a lithium salt.  
     
     
         10 . A method of making a nonaqueous electrolytic secondary battery, comprising the steps of: 
 assembling a battery by placing a negative electrode, a positive electrode, and a nonaqueous electrolytic solution comprising an electrolytic salt dissolved in a nonaqueous solvent, in a battery housing; and    charging and discharging said battery under overcharge conditions.    
     
     
         11 . A method of making a nonaqueous electrolytic secondary battery, according to  claim 10 , wherein a charging voltage during charging and discharging under overcharge conditions is set at 4.2 V or more.  
     
     
         12 . A method of making a nonaqueous electrolytic secondary battery, comprising the steps of: 
 assembling a battery by placing a negative electrode, a positive electrode, and a nonaqueous electrolytic solution comprising an electrolytic salt dissolved in a nonaqueous solvent, in a battery housing; and    applying a pulse voltage to said battery.