# US 2022/0285693 A1 · Lithium secondary battery

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- Number: US 2022/0285693 A1
- Document ID: US20220285693A1
- Status: Published application
- Kind: A1
- Application number: 17/686,030
- Filed: 2022-03-03
- Published: 2022-09-08
- Earliest claimed: 2021-03-04
- Assignees: SK On Co., Ltd.
- Applicants: SK On Co., Ltd.
- Inventors: Hee Gyoung KANG; Gi Hyeon MOON; So Hyun PARK; Mi Ryeong LEE; Jong Hyuk LEE; Chan Young JEON; Hae Suk HWANG
- Web page: https://patentgrep.com/patent/US20220285693A1

## CPC

- H01M 4/70: characterised by shape or form
- H01M 50/531: Electrode connections inside a battery casing
- H01M 4/02: Electrodes composed of, or comprising, active material
- H01M 4/13: Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M 4/131: Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
- 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 10/058: Construction or manufacture
- H01M 10/0583: of accumulators with folded construction elements except wound ones, i.e. folded positive or negative electrodes or separators, e.g. with "Z"-shaped electrodes or separators
- H01M 10/0585: of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
- H01M 10/0587: of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
- H01M 10/42: Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells (H01M10/60 takes precedence)
- H01M 50/46: Separators, membranes or diaphragms characterised by their combination with electrodes
- H01M 50/463: Separators, membranes or diaphragms characterised by their shape
- H01M 2004/021: {Physical characteristics, e.g. porosity, surface area}
- H01M 2004/027: {Negative electrodes}
- H01M 2004/028: {Positive electrodes}
- H01M 2010/4292: {Aspects relating to capacity ratio of electrodes/electrolyte or anode/cathode}
- Y02E 60/10: Energy storage using batteries
- 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

## Abstract

The lithium secondary battery includes a cathode which includes a cathode active material layer including a cathode current collector, a cathode tab protruding from one end thereof in a longitudinal direction of the cathode current collector, a second cathode portion disposed spaced apart from the cathode tab on the cathode current collector, and a first cathode portion disposed adjacent to the cathode tab on the cathode current collector and having an electrode density higher than that of the second cathode portion, and an anode disposed to face the cathode. Life-span characteristics of the lithium secondary battery may be improved by controlling the electrode density in the peripheral part of the cathode tab.

## Claims

### Claim 1

A lithium secondary battery comprising:
a cathode including a cathode current collector including a cathode tab protruding from one end thereof, and a cathode active material layer formed on the cathode current collector; and
an anode disposed to face the cathode,
wherein the cathode active material layer comprises:
a first cathode portion disposed adjacent to the cathode tab in a planar direction; and
a second cathode portion spaced apart from the cathode tab with the first cathode portion interposed therebetween in the planar direction and having an electrode density lower than that of the first cathode portion.

### Claim 2 (depends on 1)

The lithium secondary battery according to claim 1, wherein a cathode density difference defined by Formula 1 below is 1.5 to 6%:
D
dP
(
%
)
=
D
1
⁢
P
-
D
2
⁢
P
D
2
⁢
P
×
1
⁢
0
⁢
0
[
Equation
⁢
1
]
(In Equation 1, DdP is the cathode density difference, D1P is an electrode density of the first cathode portion, and D2P is an electrode density of the second cathode portion).

### Claim 3 (depends on 1)

The lithium secondary battery according to claim 1, wherein the anode comprises:
an anode current collector including an anode tab protruding from one end thereof; and
an anode active material layer formed on the anode current collector,
wherein the anode active material layer comprises:
a first anode portion disposed adjacent to the anode tab in the planar direction; and
a second anode portion spaced apart from the anode tab with the first anode portion interposed therebetween in the planar direction and having an electrode density lower than that of the first anode portion.

### Claim 4 (depends on 3)

The lithium secondary battery according to claim 3, wherein an anode density difference defined by Formula 2 below is 1.5 to 6%:
D
dN
(
%
)
=
D
1
⁢
N
-
D
2
⁢
N
D
1
⁢
N
×
1
⁢
0
⁢
0
[
Equation
⁢
2
]
(In Equation 2, DdN is the anode density difference, D1N is an electrode density of the first anode portion, and D2N is an electrode density of the second anode portion).

### Claim 5 (depends on 3)

The lithium secondary battery according to claim 3, wherein the first cathode portion and the second anode portion are overlapped with each other in a thickness direction, and the second cathode portion and the first anode portion are overlapped with each other in the thickness direction.

### Claim 6 (depends on 5)

The lithium secondary battery according to claim 5, wherein a length of the first cathode portion is the same as that of the second anode portion, and a length of the second cathode portion is the same as that of the first anode portion in the planar direction.

### Claim 7 (depends on 3)

The lithium secondary battery according to claim 3, wherein the cathode tab and the anode tab protrude in directions opposite to each other in the planar direction.

### Claim 8 (depends on 3)

The lithium secondary battery according to claim 3, wherein a length of the first cathode portion is less than or equal to that of the second cathode portion, and a length of the second anode portion is less than or equal to that of the first anode portion.

### Claim 9 (depends on 3)

The lithium secondary battery according to claim 3, wherein a thickness of the first cathode portion is smaller than that of the second cathode portion, and a thickness of the second anode portion is greater than that of the first anode portion.

### Claim 10 (depends on 9)

The lithium secondary battery according to claim 9, further comprising a separator disposed between the cathode active material layer and the anode active material layer,
wherein the separator comprises:
a first portion disposed between the first cathode portion and the second anode portion;
a second portion disposed between the second cathode portion and the first anode portion; and
a stepped portion between the first portion and the second portion.

### Claim 11 (depends on 10)

The lithium secondary battery according to claim 10, wherein the stepped portion contacts sidewalls of the second cathode portion and the second anode portion.

### Claim 12 (depends on 3)

The lithium secondary battery according to claim 3, wherein an electrode density of the first cathode portion is 3.6 g/cc or less, and an electrode density of the first anode portion is 1.7 g/cc or less.