Lithium ion secondary battery and charge system therefor

Abstract

A lithium ion secondary battery includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator interposed between the positive electrode and the negative electrode. The separator includes a polyolefin layer and an oxidation-resistant layer. The oxidation-resistant layer includes an oxidation-resistant polymer. A main chain of the oxidation-resistant polymer does not include a —CH2— group and a —CH(CH3)— group. The oxidation-resistant layer faces the positive electrode.

Description

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic circuit diagram of a charge system of the present invention

Claims

1. A lithium ion secondary battery comprising: a positive electrode; a negative electrode; a non-aqueous electrolyte; and a separator interposed between said positive electrode and said negative electrode; wherein said separator comprises a polyolefin layer and an oxidation-resistant layer,said oxidation-resistant layer comprises an oxidation-resistant polymer, a main chain of said oxidation-resistant polymer not including a —CH2— group and not including a —CH(CH3)— group, andsaid oxidation-resistant layer faces said positive electrode.

2. The lithium ion secondary battery in accordance with claim 1, wherein a cut-off-voltage of charge is set to 4.3 V or more.

3. The lithium ion secondary battery in accordance with claim 1, wherein said oxidation-resistant polymer comprises at least one selected from the group consisting of polyimide, aramid, and polyamideimide.

4. The lithium ion secondary battery in accordance with claim 1, wherein said polyolefin layer comprises polyethylene.

5. A lithium ion secondary battery comprising: a positive electrode; a negative electrode; a non-aqueous electrolyte; and a separator interposed between said positive electrode and said negative electrode; wherein said separator comprises a polyolefin layer and an oxidation-resistant layer,said oxidation-resistant layer comprises an oxidation-resistant polymer, in an IR spectrum for said oxidation-resistant polymer, each height of absorption peaks attributable to C—H stretching vibration of a —CH2— group and attributable to C—C stretching vibration of a —CH(CH3)— group being 0% to 7% of the maximum value of heights of absorption peaks in a range of 500 to 3500 cm−1, andsaid oxidation-resistant layer faces said positive electrode.

6. A charge system for a lithium ion secondary battery comprising: the lithium ion secondary battery in accordance with claim 1; and a charger for said secondary battery; wherein a cut-off-voltage of charge of said secondary battery is set to 4.3 V or more.

7. A charge system for a lithium ion secondary battery comprising: the lithium ion secondary battery in accordance with claim 5; and a charger for said secondary battery; wherein a cut-off-voltage of charge of said secondary battery is set to 4.3 V or more.