Nonaqueous electrolyte secondary battery

Abstract

In a nonaqueous electrolyte secondary battery having a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and a nonaqueous electrolyte, as the positive electrode active material or as the negative electrode active material, a mixture containing molybdenum dioxide and lithium titanate in a weight ratio (molybdenum dioxide:lithium titanate) of 90:10 to 50:50 is used.

1 . A nonaqueous electrolyte secondary battery comprising:
 a positive electrode containing a positive electrode active material; a negative electrode containing a negative electrode active material; and a nonaqueous electrolyte,   wherein as the positive electrode active material or as the negative electrode active material, a mixture containing molybdenum dioxide and lithium titanate in a weight ratio (molybdenum dioxide lithium titanate) of 90:10 to 50:50 is used.   
   
   
       2 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein in the positive electrode or negative electrode using the mixture, as a conductive agent, graphitized vapor-grown carbon fiber having lattice constant C 0  in the range of 6.7 Å≦C 0 ≦6.8 Å, a ratio L a /L c  of crystallite dimensions (L a  and L c ) in a base surface (surface a) and in a lamination direction (surface c) in the range of 4≦L a /L c ≦6 is used. 
   
   
       3 . The nonaqueous electrolyte secondary battery according to  claim 2 , wherein as the conductive agent, massive artificial graphite having lattice constant C 0  in the range of 6.7 Å≦C 0 ≦6.8 Å is used in mixture with the vapor-grown carbon fiber. 
   
   
       4 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein the mixture of molybdenum dioxide and lithium titanate is used as the negative electrode active material, and lithium cobaltate is used as the positive electrode active material. 
   
   
       5 . The nonaqueous electrolyte secondary battery according to  claim 4 , wherein when weight of lithium cobaltate used as the positive electrode active material is denoted by W LCO , weight of molybdenum dioxide used as the negative electrode active material by W MoO2 , and weight of lithium titanate used as the negative electrode active material by W LTO , 100≦(175×W LTO +210×W MoO2 )/W LCO ≦165 is satisfied. 
   
   
       6 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein as a solvent of the nonaqueous electrolyte, 5-30% by volume of ethylene carbonate is contained in the solvent. 
   
   
       7 . The nonaqueous electrolyte secondary battery according to  claim 2 , wherein as a solvent of the nonaqueous electrolyte, 5-30% by volume of ethylene carbonate is contained in the solvent. 
   
   
       8 . The nonaqueous electrolyte secondary battery according to  claim 3 , wherein as a solvent of the nonaqueous electrolyte, 5-30% by volume of ethylene carbonate is contained in the solvent. 
   
   
       9 . The nonaqueous electrolyte secondary battery according to  claim 4 , wherein as a solvent of the nonaqueous electrolyte, 5-30% by volume of ethylene carbonate is contained in the solvent. 
   
   
       10 . The nonaqueous electrolyte secondary battery according to  claim 2 , wherein the mixture of molybdenum dioxide and lithium titanate is used as the negative electrode active material, and lithium cobaltate is used as the positive electrode active material. 
   
   
       11 . The nonaqueous electrolyte secondary battery according to  claim 10 , wherein as a solvent of the nonaqueous electrolyte, 5-30% by volume of ethylene carbonate is contained in the solvent. 
   
   
       12 . The nonaqueous electrolyte secondary battery according to  claim 3 , wherein the mixture of molybdenum dioxide and lithium titanate is used as the negative electrode active material, and lithium cobaltate is used as the positive electrode active material. 
   
   
       13 . The nonaqueous electrolyte secondary battery according to  claim 12 , wherein as a solvent of the nonaqueous electrolyte, 5-30% by volume of ethylene carbonate is contained in the solvent. 
   
   
       14 . The nonaqueous electrolyte secondary battery according to  claim 10 , wherein when weight of lithium cobaltate used as the positive electrode active material is denoted by W LCO , weight of molybdenum dioxide used as the negative electrode active material by W MoO2 , and weight of lithium titanate used as the negative electrode active material by W LTO , 100≦(175×W LTO + 210 ×W MoO2 )/W LCO ≦ 165  is satisfied. 
   
   
       15 . The nonaqueous electrolyte secondary battery according to  claim 12 , wherein when weight of lithium cobaltate used as the positive electrode active material is denoted by W LCO , weight of molybdenum dioxide used as the negative electrode active material by W MoO2 , and weight of lithium titanate used as the negative electrode active material by W LTO , 100≦(175×W LTO +210×W MoO2 )/W LCO ≦165 is satisfied.