Method for producing nonaqueous electrolyte secondary battery
Disclosed is a nonaqueous electrolyte secondary battery which is suppressed in increase of internal resistance, while having high capacity retention rate and small battery swelling even after a long use. Specifically disclosed is a method for manufacturing a nonaqueous electrolyte secondary battery, which is characterized by using a positive electrode containing a positive electrode active material having an α-NaFeO2 crystal structure and the following chemical composition: LixMnaNibCocOd (wherein 0<x<1.3, a+b+c=1, 1.7≦d≦2.3), while satisfying |a−b|<0.03 and 0.33≦c<1, a negative electrode, and a nonaqueous electrolyte containing an unsaturated sultone and a sulfate ester compound.
1. A nonaqueous electrolyte secondary battery comprising a positive electrode containing a positive active material having an α-NaFO 2 -type crystal structure and being expressed by a composition formula Li x Mn a Ni b Co c O d (0<x<1.3; a+b+c=1; 1.7≦d≦2.3) while satisfying |a−b|<0.03 and 0.33≦c<1, a negative electrode, and a nonaqueous electrolyte containing an unsaturated sultone and a sulfate ester compound.
2. The nonaqueous electrolyte secondary battery according to claim 1 , wherein said unsaturated sultone is a 1,3-propene sultone derivative defined by the chemical formula 1:
wherein R 1 to R 4 each denote a hydrogen atom or the same or different alkyl group, an alkoxyl group, halogen, a halogen-containing alkyl group, or an aryl group; and n is 1 or 2.
3. The nonaqueous electrolyte secondary battery according to claim 1 or 2 , wherein said sulfate ester compound is a cyclic sulfate ester having 3 or more carbon atoms and defined by the chemical formula 2:
wherein, R 5 to R 8 each denote a hydrogen atom or the same or different alkyl group, an alkoxyl group, halogen, a halogen-containing alkyl group, or an aryl group.
4. A method for producing a nonaqueous electrolyte secondary battery comprising a step of forming a positive electrode containing a positive active material having an α-NaFO 2 -type crystal structure and being expressed by a composition formula Li x Mn a Ni b Co c O d (0<x<1.3; a+b+c=1; 1.7≦d≦2.3) while satisfying |a−b|<0.03 and 0.33≦c<1, a step of forming a negative electrode, and a step of adding a nonaqueous electrolyte containing an unsaturated sultone and a sulfate ester compound.
5. The method for producing a nonaqueous electrolyte secondary battery according to claim 4 , wherein said unsaturated sultone is a 1,3-propene sultone derivative defined by the chemical formula 1:
wherein R 1 to R 4 each denote a hydrogen atom or the same or different alkyl group, an alkoxyl group, halogen, a halogen-containing alkyl group, or an aryl group; and n is 1 or 2.
6. The method for producing a nonaqueous electrolyte secondary battery according to claim 4 or 5 , wherein said sulfate ester compound is a cyclic sulfate ester having 3 or more carbon atoms and defined by the chemical formula 2:
wherein, R 5 to R 8 each denote a hydrogen atom or the same or different alkyl group, an alkoxyl group, halogen, a halogen-containing alkyl group, or an aryl group.