# US 2017/0373352 A1 · Lithium ion secondary battery

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- Number: US 2017/0373352 A1
- Document ID: US20170373352A1
- Status: Published application
- Kind: A1
- Application number: 15/622,481
- Filed: 2017-06-14
- Published: 2017-12-28
- Earliest claimed: 2016-06-23
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Toyota Jidosha Kabushiki Kaisha
- Inventors: Hideyuki SAKA; Yukihiro OKADA; Keiichi TAKAHASHI; Kaoru INOUE
- Web page: https://patentgrep.com/patent/US20170373352A1

## CPC

- H01M 10/4235: {Safety or regulating additives or arrangements in electrodes, separators or electrolyte (H01M10/4242 takes precedence)}
- H01M 4/364: {as mixtures}
- H01M 4/505: of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
- H01M 4/525: of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 10/0587: of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
- H01M 50/578: in response to pressure
- H01M 2200/20: Pressure-sensitive devices
- H01M 2220/20: Batteries in motive systems, e.g. vehicle, ship, plane
- Y02E 60/10: Energy storage using batteries
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Provided is a lithium ion secondary battery which has a low internal resistance in a low-SOC region and a sufficiently large amount of gas generated during overcharge. The lithium ion secondary battery disclosed herein includes an electrode body having a positive electrode and a negative electrode, and a nonaqueous electrolytic solution. The lithium ion secondary battery further includes a pressure-type safety mechanism. The nonaqueous electrolytic solution includes a gas generating agent. The positive electrode has a positive electrode active material layer including a positive electrode active material. The positive electrode active material includes a lithium transition metal composite oxide represented by LiNiaCobMncO2 wherein a, b and c satisfy the following conditions: 0.35≦a≦0.45, 0.15≦b≦0.25, 0.35≦c≦0.45, and a+b+c=1, and a lithium transition metal composite oxide represented by LiNixCoyMnzO2 wherein x, y and z satisfy the following conditions: 0.35≦x≦0.45, 0.45≦y≦0.55, 0.05≦z≦0.15, and x+y+z=1, and the mass ratio of the oxides is 60:40 to 85:15.

## Claims

### Claim 1

A lithium ion secondary battery comprising:
an electrode body having a positive electrode and a negative electrode; and
a nonaqueous electrolytic solution,
the lithium ion secondary battery further comprising a pressure-type safety mechanism for changing an energization state according to a battery internal pressure,
wherein the nonaqueous electrolytic solution includes a gas generating agent which reacts at a voltage equal to or higher than a predetermined voltage to generate a gas,
the positive electrode has a positive electrode active material layer including a positive electrode active material,
the positive electrode active material includes a first lithium transition metal composite oxide represented by the general formula LiNiaCobMncO2 wherein a, b and c are values satisfying the following conditions: 0.35≦a≦0.45, 0.15≦b≦0.25, 0.35≦c≦0.45, and a+b+c=1, and a second lithium transition metal composite oxide represented by the general formula LiNixCoyMnzO2 wherein x, y and z are values satisfying the following conditions: 0.35≦x≦0.45, 0.45≦y≦0.55, 0.05≦z≦0.15, and x+y+z=1, and
a mass ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide is 60:40 to 85:15.

### Claim 2 (depends on 1)

The lithium ion secondary battery according to claim 1, wherein the mass ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide is 60:40 to 75:25.