Lithium secondary battery

Abstract

The present invention provides a lithium secondary battery comprising a nonaqueous electrolytic solution containing a compound which is oxidized at a voltage higher than a charge end voltage of the lithium secondary battery and a compound which inhibits reactions at voltages lower than said charge end voltage.

What is claimed as new and desired to be protected by Letters Patent of the United States is:  
     
         1 . A lithium secondary battery comprising a nonaqueous electrolytic solution containing a compound which is oxidized at a voltage higher than a charge end voltage of the lithium secondary battery and a compound which inhibits reactions at voltages lower than said charge end voltage.  
     
     
         2 . The lithium secondary battery of  claim 1  wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         3 . The lithium secondary battery according to  claim 2  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         4 . The lithium secondary battery according to  claim 2  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         5 . The lithium secondary battery according to  claim 4  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         6 . A lithium secondary battery having a nonaqueous electrolytic solution characterized in that the lithium secondary battery has a charge capacity of C 1  when it (in discharged state) is charged with constant current until a voltage V 1  of 1.2V is reached and the lithium secondary battery has a charge capacity of C 2  when it is charged further (at a voltage higher than V 1 ) until it cannot be charged any longer, with the ratio (ξ) of C 1 /C 2  being lower than 0.7.  
     
     
         7 . The lithium secondary battery of  claim 6  wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         8 . The lithium secondary battery according to  claim 7  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         9 . The lithium secondary battery according to  claim 7  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         10 . The lithium secondary battery according to  claim 9  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, to diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         11 . A lithium secondary battery comprising a nonaqueous electrolytic solution containing a compound which is oxidized at a voltage higher than a charge end voltage of the lithium secondary battery and a compound which inhibits reactions at voltages lower than said charge end voltage wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         12 . The lithium secondary battery according to  claim 11  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         13 . The lithium secondary battery according to  claim 11  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         14 . The lithium secondary battery according to  claim 13  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         15 . A lithium secondary battery having a nonaqueous electrolytic solution characterized in that the lithium secondary battery has a charge capacity of C 1  when it (in discharged state) is charged with constant current until a voltage V 1  of 1.2V is reached and the lithium secondary battery has a charge capacity of C 2  when it is charged further (at a voltage higher than V 1 ) until it cannot be charged any longer, with the ratio (ξ) of C 1 /C 2  being lower than 0.7 and wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         16 . The lithium secondary battery according to  claim 15  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         17 . The lithium secondary battery according to  claim 15  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         18 . The lithium secondary battery according to  claim 17  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         19 . An electrical appliance using a lithium secondary battery as a power source which comprises a means for protecting the lithium secondary batteries from overcharging and overdischarging being free from temperature and pressure detection of the batteries, a means for detecting voltages or current of the batteries and a means for controlling to turn on or off the batteries said lithium secondary battery comprising a nonaqueous electrolytic solution containing a compound which is oxidized at a voltage higher than a charge end voltage of the lithium secondary battery and a compound which inhibits reactions at voltages lower than said charge end voltage.  
     
     
         20 . The electrical appliance of  claim 19  wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         21 . The electrical appliance according to  claim 20  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         22 . The electrical appliance according to  claim 20  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         23 . The electrical appliance according to  claim 22  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         24 . The electrical appliance according to  claim 19  wherein said appliance is an electric car.  
     
     
         25 . An electrical appliance using a lithium secondary battery as a power source which comprises a means for protecting the lithium secondary batteries from overcharging and overdischarging being free from temperature and pressure detection of the batteries, a means for detecting voltages or current of the batteries and a means for controlling to turn on or off the said lithium secondary battery comprising a nonaqueous electrolytic solution characterized in that the lithium secondary battery has a charge capacity of C 1  when it (in discharged state) is charged with constant current until a voltage V 1  of 1.2V is reached and the lithium secondary battery has a charge capacity of C 2  when it is charged further (at a voltage higher than V 1 ) until it cannot be charged any longer, with the ratio (ξ) of C 1 /C 2  being lower than 0.7.  
     
     
         26 . The electrical appliance of  claim 25  wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         27 . The electrical appliance according to  claim 26  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         28 . The electrical appliance according to  claim 26  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         29 . The electrical appliance according to  claim 28  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         30 . The electrical appliance according to  claim 25  wherein said appliance is an electric car.  
     
     
         31 . An electrical appliance using a lithium secondary battery as a power source which comprises a means for protecting the lithium secondary batteries from overcharging and overdischarging being free from temperature and pressure detection of the batteries, a means for detecting voltages or current of the batteries and a means for controlling to turn on or off the batteries said lithium secondary battery comprising a nonaqueous electrolytic solution containing a compound which is oxidized at a voltage higher than a charge end voltage of the lithium secondary battery and a compound which inhibits reactions at voltages lower than said charge end voltage wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         32 . The electrical appliance according to  claim 31  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         33 . The electrical appliance according to  claim 31  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         34 . The electrical appliance according to  claim 33  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         35 . The electrical appliance according to  claim 31  wherein said appliance is an electric car.  
     
     
         36 . An electrical appliance using a lithium secondary battery as a power source which comprises a means for protecting the lithium secondary batteries from overcharging and overdischarging being free from temperature and pressure detection of the batteries, a means for detecting voltages or current of the batteries and a means for controlling to turn on or off the batteries said lithium secondary battery comprising a nonaqueous electrolytic solution characterized in that the lithium secondary battery has a charge capacity of C 1  when it (in discharged state) is charged with constant current until a voltage V 1  of 1.2V is reached and the lithium secondary battery has a charge capacity of C 2  when it is charged further (at a voltage higher than V 1 ) until it cannot be charged any longer, with the ratio (4) of C 1 /C 2  being lower than 0.7 and wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         37 . The electrical appliance according to  claim 36  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         38 . The electrical appliance according to  claim 36  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         39 . The electrical appliance according to  claim 38  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         40 . The electrical appliance according to  claim 36  wherein said appliance is an electric car.  
     
     
         41 . A method of fabricating a lithium secondary battery comprising the steps of: 
 providing an anode;    providing a cathode;    providing a separator; and    providing a nonaqueous electrolytic solution containing a compound which is oxidized at a voltage higher than a charge end voltage of the lithium secondary battery and a compound which inhibits reactions at voltages lower than said charge end voltage.    
     
     
         42 . The method of  claim 41  wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         43 . The method according to  claim 42  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         44 . The method according to  claim 42  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         45 . The method according to  claim 44  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         46 . A method of fabricating a lithium secondary battery comprising the steps of: 
 providing an anode;    providing a cathode;    providing a separator; and    providing a nonaqueous electrolytic solution characterized in that the lithium secondary battery has a charge capacity of C 1  when it (in discharged state) is charged with constant current until a voltage V 1  of 1.2V is reached and the lithium secondary battery has a charge capacity of C 2  when it is charged further (at a voltage higher than V 1 ) until it cannot be charged any longer, with the ratio (ξ) of C 1 /C 2  being lower than 0.7.    
     
     
         47 . The method of  claim 46  wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.  
       Rf 1 —X—Rf 2   (1)  (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         48 . The method according to  claim 47  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         49 . The method according to  claim 47  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         50 . The method according to  claim 49  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         51 . A method of fabricating a lithium secondary battery comprising the steps of: 
 providing an anode;    providing a cathode;    providing a separator; and    providing a nonaqueous electrolytic solution containing a compound which is oxidized at a voltage higher than a charge end voltage of the lithium secondary battery and a compound which inhibits reactions at voltages lower than said charge end voltage wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.    Rf 1 —X—Rf 2   (1)    (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         52 . The method according to  claim 51  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         53 . The method according to  claim 51  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         54 . The method according to  claim 53  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.  
     
     
         55 . A method of fabricating a lithium secondary battery comprising the steps of: 
 providing an anode;    providing a cathode;    providing a separator; and    providing a nonaqueous electrolytic solution characterized in that the lithium secondary battery has a charge capacity of C 1  when it (in discharged state) is charged with constant current until a voltage V 1  of 1.2V is reached and the lithium secondary battery has a charge capacity of C 2  when it is charged further (at a voltage higher than V 1 ) until it cannot be charged any longer, with the ratio (ξ) of C 1 /C 2  being lower than 0.7 and wherein said nonaqueous electrolytic solution is composed of a fluorinated solvent represented by the chemical formula (1) and an aromatic compound represented by the chemical formula (2) below.    Rf 1 —X—Rf 2   (1)    (where Rf 1  denotes an entirely or partly fluorinated C 2-10  alkyl group, Rf 2  denotes an entirely or partly fluorinated C 1-5  alkyl group, and X denotes an ether or ester.)                          (where R 1 , R 2 , R 3 , and R 4  each denotes hydrogen, fluorine, chlorine, bromine, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, an alkyl-substituted phenyl group or phenoxy group, a C 1-4  carboxyl group, a benzyl group, or an alkyl-substituted or alkoxyl-substituted silyl group; and R 5  and R 6  each denotes hydrogen, fluorine, chlorine, bromine, or a C 1-3  alkyl group.)    
     
     
         56 . The method according to  claim 55  wherein the fluorinated solvent is methyl nanofluorobutyl ether.  
     
     
         57 . The method according to  claim 55  wherein the aromatic compound is a phenylsilane derivative represented by the chemical formula (3) below.  
       
         
           
           
               
               
           
         
         (where R 7 , R 8 , and R 9  each denotes hydrogen, a C 1-3  alkyl group or alkoxyl group, a phenyl group, a phenoxy group, a benzyl group, fluorine, chlorine, bromine, or a C 1-3  alkyl-substituted phenyl group, phenoxy group, or benzyl group; and R 10 , R 11 , R 12 , R 13 , and R 14  each denotes a C 1-3  alkoxyl group, a phenyl group, a benzyl group, or a phenyl group, phenoxy group, or benzyl group substituted with fluorine, chlorine, or bromine.)  
       
     
     
         58 . The method according to  claim 57  wherein said phenylsilane derivative is selected from the group comprising diphenylsilane, diphenylmethylsilane, 4-methylpheyltrimethylsilane, and diphenyldimethoxysilane.