Nonaqueous electrolyte secondary battery using lithium cobalt oxide as a positive active material and a nonaqueous electrolyte containing a sulfonyl-containing compound
View Patent ↗A nonaqueous electrolyte secondary battery including a negative electrode containing a graphite material as the negative active material, a positive electrode containing lithium cobalt oxide as a main component of the positive active material and a nonaqueous electrolyte solution, the battery being characterized in that the lithium cobalt oxide contains a group IVA element and a group IIA element of the periodic table, the nonaqueous electrolyte solution contains 0.2-1.5% by weight of a sulfonyl-containing compound and preferably further contains 0.5-4% by weight of vinylene carbonate.
1. A nonaqueous electrolyte secondary battery including a negative electrode containing a graphite material as the negative active material, a positive electrode containing lithium cobalt oxide as a main component of the positive active material and a nonaqueous electrolyte solution, said battery being characterized in that said lithium cobalt oxide contains 0.05-2.0 mol. % of a group IVA element selected from the group consisting of Ti, Zr and Hf and 0.1-2.0 mol. % of a group IIA element of the periodic table with respect to a total amount of the metal elements other than lithium and said nonaqueous electrolyte solution contains 0.2-1.5% by weight of a sulfonyl-containing compound, and wherein said lithium cobalt oxide is obtained by mixing raw materials for preparing a lithium cobalt oxide with raw materials of said group IVA element and said group IIA element and heat treating the mixed raw materials.
2. The nonaqueous electrolyte secondary battery as recited in claim 1 , characterized in that, in said positive active material, said group IVA element is zirconium and said group IIA element is magnesium.
3. The nonaqueous electrolyte secondary battery as recited in claim 1 , characterized in that said nonaqueous electrolyte solution further contains 0.5-4% by weight of vinylene carbonate.
4. The nonaqueous electrolyte secondary battery as recited in claim 1 , characterized in that said sulfonyl-containing compound is at least one of 1,4-butanediol dimethanesulfonate and divinyl sulfone.
5. The nonaqueous electrolyte secondary battery as recited in claim 1 , characterized in that said nonaqueous electrolyte solution contains, as said sulfonyl-containing compound, 1,4-butanediol dimethanesulfonate in the amount of 0.5-1.5% by weight.
6. The nonaqueous electrolyte secondary battery as recited in claim 1 , characterized in that said nonaqueous electrolyte solution contains, as said sulfonyl-containing compound, divinyl sulfone in the amount of 0.2-0.5% by weight.
7. The nonaqueous electrolyte secondary battery as recited in claim 1 , characterized in that said nonaqueous electrolyte solution contains, as a solvent, diethyl carbonate.
8. The nonaqueous electrolyte secondary battery as recited in claim 1 , characterized in that said positive active material and negative active material are contained such that a ratio in charge capacity of the negative electrode to the positive electrode is 1.0-1.2 when an end-of-charge voltage is prescribed at 4.3 V.
9. The nonaqueous electrolyte secondary battery as recited in claim 1 , characterized in that said positive active material and negative active material are contained such that a ratio in charge capacity of the negative electrode to the positive electrode is 1.0-1.2 when an end-of-charge voltage is prescribed at 4.4 v.
10. The nonaqueous electrolyte secondary battery as recited in claim 2 , characterized in that said nonaqueous electrolyte solution further contains 0.5-4% by weight of vinylene carbonate.