Non-aqueous electrolyte secondary battery
In an electrolyte of a non-aqueous electrolyte secondary battery using a cyclic carboxylic-acid ester exerting high conductivity under a low temperature condition, for suppressing reductive decomposition of the cyclic carboxylic acid ester, a cyclic carbonic acid ester having at least one carbon-carbon unsaturated bond is contained, and for suppressing excessive polymerization reaction of the cyclic carbonic acid ester having at least one carbon-carbon unsaturated bond, a cyclic carbonic acid ester having no carbon-carbon unsaturated bond is further contained.
1. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode and a non-aqueous electrolyte,
wherein said non-aqueous electrolyte comprises a non-aqueous solvent and a solute dissolved in said non-aqueous solvent,
wherein said non-aqueous solvent comprises: (A) a cyclic carboxylic acid ester; (B) 0.5 to 20 volume percent of the total volume of non-aqueous solvent of a cyclic carbonic acid ester having at least one carbon-carbon unsaturated bond; and (C) a cyclic carbonic acid ester having no carbon-carbon unsaturated bond,
and wherein said cyclic carbonic acid ester having at least one carbon-carbon unsaturated bond (B) comprises vinylethylene carbonate and vinylene carbonate.
2. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said cyclic carboxylic acid ester (A) is at least one selected from the group consisting of γ-butyrolactone and a derivative of γ-butyrolactone represented by the formula (1):
where R 1 to R 6 are, independently, a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an acetyl group having 1 to 6 carbon atoms.
3. The non-aqueous electrolyte secondary battery in accordance with claim 2 , wherein said derivative of γ-butyrolactone is γ-valerolactone.
4. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said cyclic carbonic acid ester having at least one carbon-carbon unsaturated bond (B) further comprises divinylethylene carbonate.
5. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said cyclic carbonic acid ester having no carbon-carbon unsaturated bond (C) is at least one selected from the group consisting of propylene carbonate, ethylene carbonate and butylene carbonate.
6. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said cyclic carboxylic acid ester (A) is at least one selected from the group consisting of γ-butyrolactone and γ-valerolactone, said cyclic carbonic acid ester having at least one carbon-carbon unsaturated bond (B) further comprises divinylethylene carbonate, and said cyclic carbonic acid ester having no carbon-carbon unsaturated bond (C) is at least one selected from the group consisting of propylene carbonate and ethylene carbonate.
7. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said non-aqueous solvent further comprises a linear carbonic acid ester (D).
8. The non-aqueous electrolyte secondary battery in accordance with claim 7 , wherein said linear carbonic acid ester (D) is at least one selected from the group consisting of dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate.
9. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said non-aqueous solvent further comprises a glime (E).
10. The non-aqueous electrolyte secondary battery in accordance with claim 9 , wherein said glime (E) is at least one selected from the group consisting of diglime, triglime and tetraglime.
11. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said positive electrode comprises a lithium-containing transition metal oxide and said negative electrode comprises graphite.
12. The non-aqueous electrolyte secondary battery in accordance with claim 11 , wherein said lithium-containing transition metal oxide is represented by the formula:
Li a (CO l−x−y Mg x M y ) b O c
where M is at least one selected from the group consisting of Mn, Ni, Y, Yb, Ca, Al, Ti, Cu, Zn, Sr and Ba, 0≦a≦1.05, 0.005≦x≦0.15, 0≦y≦0.25, 0.85≦b≦1.1 and 1.8≦c≦2.1.
13. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said non-aqueous electrolyte comprises LiPF 6 and LiBF 4 in a molar ratio of 1:9 to 9:1 as said solute.
14. The non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said non-aqueous solvent further comprises a derivative of benzene comprising a phenyl group and a cyclic compound group contiguous to said phenyl group.