Polymer gel electrolyte and polymer secondary battery using the same

Abstract

A polymer gel electrolyte, comprising a polymer gel including an aprotic organic solvent, a carrier salt and a sulfur-containing organic compound having at least one —O—SO2— in its chemical structure, for instance, a straight-chain sulfonic acid ester or a cyclic sulfonic acid ester, and a lithium polymer secondary battery using the polymer gel electrolyte and having improved rate performance and cycle performance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.

FIG. 1 is illustrative of the construction of the positive electrode in the lithium polymer battery of the invention.

FIG. 2 is illustrative of the construction of the negative electrode in the lithium polymer battery of the invention.

FIG. 3 is illustrative of the construction of a battery element of the inventive lithium polymer battery after rolled up.

FIG. 4 is illustrative of a step of applying a covering film around the inventive lithium polymer battery.

Claims

1. A polymer gel electrolyte, characterized by comprising an aprotic organic solvent, a carrier salt and a sulfur-containing organic compound having at least one —O—SO2— in its chemical structure.

2. The polymer gel electrolyte according to claim 1, characterized in that the sulfur-containing organic compound is a chain sulfonic acid ester.

3. The polymer gel electrolyte according to claim 1, characterized in that the sulfur-containing organic compound has a cyclic structure represented by either one of the following chemical formulae 1 and 2

4. The polymer gel electrolyte according to claim 3, the sulfur-containing organic compound having a cyclic structure is at least one of 1,3-propane sultone or 1,4-butane sultone.

5. The polymer gel electrolyte according to claim 3, characterized in that the sulfur-containing organic compound having a cyclic structure is at least one cyclic disulfonic acid ester selected from methylenemethane disulfonate, ethylenemethane disulfonate and propylene-methane disulfonate.

6. The polymer gel electrolyte according to claim 1, characterized in that the sulfur-containing organic compound is contained in an amount of 0.005 part by mass to 10 parts by mass inclusive per 100 parts by weight of a total of the aprotic organic solvent plus carrier salt.

7. The polymer gel electrolyte according to claim 1, characterized by further comprising vinylene carbonate or its derivative.

8. The polymer gel electrolyte according to claim 1, characterized in that the aprotic organic solvent contains at least one selected from the group consisting of cyclic polycarbonates, chain carbonates, aliphatic carboxylic acid esters, γ-lactones, cyclic ethers and chain ethers as well as their fluorine derivatives.

9. The polymer gel electrolyte according to claim 1, characterized in that the carrier salt contains at least one substance selected from the group consisting of LiPF6, LiBF4, LiAsF6, LiSbF6, LiClO4, LiAlCl4, and LiN(CnF2n+1SO2) (CmF2m+1SO2) where n and m are each a natural number.

10. The polymer gel electrolyte according to claim 1, characterized in that a polymer that forms a polymer gel is at least one selected from the group consisting of polyacrylate, polyethylene oxide, and polypropylene oxide.

11. A polymer secondary battery, characterized by including a polymer gel electrolyte as recited in claim 1, and further comprising a positive electrode including a lithium-containing composite oxide as a positive electrode active substance and a negative electrode containing as a negative electrode active substance a substance capable of inserting or deinserting lithium.