Secondary battery

Patent metadata

Field	Value
Publication number	US-12580197-B2
Application number	US-202519048203-A
Country	US
Kind code	B2
Filing date	Feb 7, 2025
Priority date	Jan 28, 2022
Publication date	Mar 17, 2026
Grant date	Mar 17, 2026

Abstract

Provided is a secondary battery including: a positive electrode including a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector and including a positive electrode active material, a positive electrode conductive material and a positive electrode binder, wherein the positive electrode binder is fiberized and binds the positive electrode active material and the positive electrode conductive material; a negative electrode including a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector and including a plurality of granules including a negative electrode active material and a negative electrode binder, and formed as the negative electrode binder binds the negative electrode active material; and a separator disposed between the positive electrode and the negative electrode.

First claim

The invention claimed is:

1 . A secondary battery comprising:
a positive electrode comprising:
a positive electrode current collector, and
a positive electrode active material layer located on the positive electrode current collector and comprising a positive electrode active material, a positive electrode conductive material, and a positive electrode binder comprising polytetrafluoroethylene (PTFE),
wherein the positive electrode active material layer is formed by a dry process,
wherein the positive electrode binder is fiberized and binds the positive electrode active material and the positive electrode conductive material,
wherein the positive electrode has a bending resistance lower than 10 mm Φ,
wherein the positive electrode binder comprised in the positive electrode active material layer has a crystallinity of 10% or lower;
a negative electrode comprising:
a negative electrode current collector, and
a negative electrode active material layer located on the negative electrode current collector and comprising a plurality of granules comprising a negative electrode active material and a negative electrode binder, wherein the negative electrode active material layer is formed by a spray-drying process,
wherein the plurality of granules have a structure in which the negative electrode binder binds the negative electrode active material; and
a separator disposed between the positive electrode and the negative electrode.

2 . The secondary battery according to claim 1 , wherein the bending resistance of the positive electrode is defined according to JIS K5600-5-1.

3 . The secondary battery according to claim 1 , wherein the bending resistance of the positive electrode is defined by:
preparing a rectangular positive electrode sample with a size of 100 mm×50 mm; preparing measuring rods having diameters of 2, 3, 4, 5, 6, 8, 10, 12, 16, 20, 25 and 32 mm respectively, contacting the positive electrode sample with a measuring rod with a largest diameter, and determining whether a crack occurs in a mixed film of the positive electrode sample when both ends of the positive electrode sample are lifted; repeating the determining of whether the crack occurs in the mixed film of the positive electrode sample using a measuring rod with a next largest diameter if the crack has not occurred in the previous step; and defining the bending resistance as a minimum diameter of the measuring rod when no crack occurs in the mixed film of the positive electrode sample.

4 . The secondary battery according to claim 1 , wherein the positive electrode active material layer has a porosity of 20-35%.

5 . The secondary battery according to claim 1 , wherein a loading amount of the positive electrode active material in the positive electrode active material layer is 3-15 mAh/cm 2 .

6 . The secondary battery according to claim 1 , wherein an interfacial resistance between the positive electrode active material layer and the positive electrode current collector is 5 Ω·cm 2 or lower.

7 . The secondary battery according to claim 1 , wherein
the positive electrode binder comprises a fluorine-based positive electrode binder, the positive electrode active material layer has a positive electrode QBR (quantified binder ratio) of 1.1 or lower, and the positive electrode QBR is defined by the following equation: Positive electrode QBR=CB s /CB f wherein CB s is an average fluorine content in a surface region of the positive electrode active material layer from an outermost surface of the positive electrode active material layer to 15% of a total thickness of the positive electrode active material layer, and CB f is an average fluorine content in a floor region of the positive electrode active material layer from an interface of the positive electrode active material layer contacting with the positive electrode current collector to 15% of the total thickness of the positive electrode active material layer.

8 . The secondary battery according to claim 1 , wherein the positive electrode conductive material comprises one or more of activated carbon, graphite, carbon black, ketjen black or carbon nanotube.

9 . The secondary battery according to claim 1 , wherein the positive electrode active material layer comprises 85-98 parts by weight of the positive electrode active material 0.5-5 parts by weight of the positive electrode conductive material and 0.5-10 parts by weight of the positive electrode binder.

10 . The secondary battery according to claim 1 , wherein a conductive primer is provided wholly or partially coated on the positive electrode current collector.

11 . The secondary battery according to claim 1 , wherein the granule comprised in the negative electrode has: a core part comprising the negative electrode active material; and a surface part located wholly or partially outside the core part and comprising the negative electrode binder binding the negative electrode active material.

12 . The secondary battery according to claim 11 , wherein the negative electrode binder comprised in the surface part of the granule is connected with the negative electrode binder in the surface part of a neighboring granule, so that the negative electrode binder is distributed in the active material layer to have a network structure.

13 . The secondary battery according to claim 1 , wherein
the negative electrode binder has a double bond, the negative electrode active material layer has a negative electrode QBR (quantified binder ratio) of 2.0 or lower, and the negative electrode QBR is defined by the following equation: Negative electrode QBR=AB s /AB f wherein AB s is an average double bond content of the negative electrode binder in a surface region of the negative electrode active material layer from an outermost surface of the negative electrode active material layer to 15% of a total thickness of the negative electrode active material layer, and AB f is an average double bond content of the negative electrode binder in a floor region of the negative electrode active material layer from an interface of the negative electrode active material layer contacting with the negative electrode current collector to 15% of the total thickness of the negative electrode active material layer.

14 . The secondary battery according to claim 1 , wherein
the granule has a higher electrode binder content (wt %) in a surface part than in a core part based on 100 wt % of the negative electrode active material and the negative electrode binder, and the surface part is a region near a surface of the granule from a granule surface to a predetermined depth toward the center of the granule, and the core part is a region other than the surface part.

15 . The secondary battery according to claim 1 , wherein the negative electrode active material layer comprises the plurality of granules comprising the negative electrode active material, a negative electrode conductive material, and the negative electrode binder, and formed as the negative electrode binder binds the negative electrode active material and the negative electrode conductive material.

16 . The secondary battery according to claim 15 , wherein the negative electrode active material layer comprises 85-98 parts by weight of the negative electrode active material, 0.5-5 parts by weight of the negative electrode conductive material and 0.5-10 parts by weight of the negative electrode binder.

17 . The secondary battery according to claim 1 , wherein
a primer layer is formed wholly or partially on at least one side

Assignees

• Lg Energy Solution Ltd

Inventors

• Kim Hak-Yoon
• Kang Seong-Wook
• Shin Dong-Oh
• Lee Nam-Jeong
• Park Moon-Soo

Classifications

• H01M4/0419

  involving spraying · CPC title

• H01M4/131

  Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M10/052

  Li-accumulators · CPC title