# US 2021/0280919 A1 · Lithium secondary battery

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2021/0280919 A1
- Document ID: US20210280919A1
- Status: Published application
- Kind: A1
- Application number: 17/261,355
- Filed: 2019-02-20
- Published: 2021-09-09
- Earliest claimed: 2018-07-30
- Assignees: Panasonic Intellectual Property Management Co., Ltd.
- Applicants: Panasonic Intellectual Property Management Co., Ltd.
- Inventors: Tomohiro Harada
- Web page: https://patentgrep.com/patent/US20210280919A1

## CPC

- H01M 10/0431: {Cells with wound or folded electrodes (H01M10/045 takes precedence)}
- H01M 10/0587: of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
- H01M 4/131: Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
- H01M 4/485: of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence)
- H01M 10/052: Li-accumulators
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 50/531: Electrode connections inside a battery casing
- H01M 2004/028: {Positive electrodes}
- 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

A lithium secondary battery with a positive electrode active material including a composite oxide containing lithium and a transition metal. A molar ratio: MLi/MTM of a total lithium amount per unit area MLi in a positive electrode and a negative electrode to a transition metal amount per unit area MTM in the positive electrode is 1.1 or less. The negative electrode includes a negative electrode current collector larger in area than the positive electrode mixture layer. In the wound electrode group in an unwound state, center lines dividing the positive electrode mixture layer and the negative electrode current collector along their winding direction into two halves are not on the same straight line. The negative electrode lead is connected at its one end to a non-facing region not facing the positive electrode mixture layer of the negative electrode current collector.

## Claims

### Claim 1

A lithium secondary battery, comprising: a wound electrode group; and a non-aqueous electrolyte,
the wound electrode group including:
a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, a positive electrode lead electrically connected to the positive electrode, and a negative electrode lead electrically connected to the negative electrode, the positive electrode and the negative electrode being wound with the separator between the positive electrode and the negative electrode, wherein
the positive electrode includes a positive electrode mixture layer containing a positive electrode active material, and a positive electrode current collector;
the positive electrode active material includes a composite oxide containing lithium and a transition metal;
a molar ratio: MLi/MTM of a total lithium amount per unit area MLi in the positive electrode and the negative electrode to a transition metal amount per unit area MTM in the positive electrode is 1.1 or less;
the negative electrode includes a negative electrode current collector;
the negative electrode current collector is larger in area than the positive electrode mixture layer;
in the wound electrode group in an unwound state,
a center line dividing the positive electrode mixture layer along a winding direction into two halves and a center line dividing the negative electrode current collector along the winding direction into two halves are not on a same straight line; and
the negative electrode lead is connected at its one end to a non-facing region not facing the positive electrode mixture layer of the negative electrode current collector.

### Claim 2 (depends on 1)

The lithium secondary battery according to claim 1, wherein
the negative electrode current collector includes a first end along the winding direction, and a second end opposite to the first end;
the non-facing region includes a belt-like first region including the first end and not facing the positive electrode mixture layer in a wound state, and a belt-like second region including the second end and not facing the positive electrode mixture layer in a wound state; and
the negative electrode lead is connected at the one end to the first region or the second region.

### Claim 3 (depends on 2)

The lithium secondary battery according to claim 2, wherein the second region has a length L2 in a winding axis direction, and the first region has a length L1 in the winding axis direction, the length L2 being larger than the length L1, and the negative electrode lead is connected at the one end to the second region.

### Claim 4 (depends on 3)

The lithium secondary battery according to claim 3, wherein a ratio: L2/L1 of the length L2 to the length L1 is 5 or more and 35 or less.

### Claim 5 (depends on 1)

The lithium secondary battery according to claim 1, wherein
the positive electrode current collector includes a major portion and an extended portion extending from part of an end along the winding direction of the major portion,
at least part of the extended portion is without the positive electrode mixture layer and overlaps the non-facing region of the negative electrode current collector, and
the positive electrode lead is connected at its one end to the extended portion.