Negative electrode for lithium ion secondary battery

Inventors: Mi-Ru Jo (Daejeon, KR); Tae-Gyun Noh (Daejeon, KR); Jeong-In Han (Daejeon, KR)

Assignee: LG ENERGY SOLUTION, LTD.

H01M4/587 H01M4/0404 H01M4/133 H01M10/0525 H01M2004/021 H01M2004/027

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Quick Facts

Patent No.: US 12683164
App. No.: 18/012,217
Granted: Jul 14, 2026
Kind: B2

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Abstract

The negative electrode includes a carbon-coated artificial graphite in combination with a non-coated artificial graphite as a negative electrode active material, and thus shows an effect of preventing deterioration caused by deformation of a carbon-coated artificial graphite occurring upon the pressing by virtue of the introduction of the non-coated artificial graphite. The negative electrode maintains electrochemical characteristics well, and for example, is prevented from deterioration of a carbon-coated artificial graphite, and thus is suitable for manufacturing a battery for quick charging.

Claims (38)

1 . A negative electrode for a lithium-ion secondary battery, comprising a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector,

wherein the negative electrode active material layer comprises a lower layer disposed on the at least one surface of the negative electrode current collector and an upper layer disposed on a top of the lower layer,

each of the lower layer and the upper layer independently includes a negative electrode mixture containing a negative electrode active material, a conductive material and a binder, and

the negative electrode active material includes a negative electrode active material a and a negative electrode active material b,

the negative electrode active material a is an artificial graphite having a surface on which a carbonaceous material is coated,

the negative electrode active material b is an artificial graphite having a surface on which the carbonaceous material is not coated,

wherein a content of the negative electrode active material b in the upper layer is 40-60 wt % based on a total content of the negative electrode active material a and the negative electrode active material b in the upper layer,

wherein a content of the negative electrode active material b in the lower layer is 40-60 wt % based on a total content of the negative electrode active material a and the negative electrode active material b in the lower layer,

wherein the upper layer has a higher content of the negative electrode active material a than a content of the negative electrode active material a in the lower layer,

wherein a binder content ratio of the negative electrode mixture in the lower layer is relatively higher than a binder content ratio of the negative electrode mixture in the upper layer,

wherein the lower layer includes the binder in an amount of 2.4 to 3 wt % based on 100 wt % of the negative electrode mixture in the lower layer,

the carbonaceous material coated on the artificial graphite is a carbon coating layer, and

the carbon coating layer is included in an amount of 1 to 10 wt % based on 100 wt % of the negative electrode active material a.

2 . The negative electrode for a lithium-ion secondary battery according to claim 1 , wherein each of the artificial graphite of the negative electrode active material a and the artificial graphite of the negative electrode active material b independently has a degree of orientation, which is a ratio of I 110 to I 004 of particles of the artificial graphite of 3-25.

3 . The negative electrode for a lithium-ion secondary battery according to claim 1 , wherein each of the artificial graphite of the negative electrode active material a and the artificial graphite of the negative electrode active material b independently has a degree of orientation, which is a ratio of I 110 to I 004 of particles of the artificial graphite, of 12-25.

4 . The negative electrode for a lithium-ion secondary battery according to claim 1 , wherein each of the artificial graphite of the negative electrode active material a and the artificial graphite of the negative electrode active material b independently has a specific surface area of 0.5-5 m 2 /g.

5 . The negative electrode for a lithium-ion secondary battery according to claim 1 , wherein the carbonaceous material comprises a low-crystallinity carbonaceous material and/or an amorphous carbonaceous material.

6 . The negative electrode for a lithium-ion secondary battery according to claim 1 , wherein the upper layer and the lower layer comprise the same negative electrode active material a and the same negative electrode active material b.

7 . A method for manufacturing the negative electrode as defined in claim 1 , comprising: preparing each of a first negative electrode slurry for forming a lower layer negative electrode mixture and a second negative electrode slurry for forming an upper layer negative electrode mixture; and sequentially or simultaneously applying the first negative electrode slurry and the second negative electrode slurry onto the negative electrode current collector, followed by drying.

8 . A secondary battery comprising: the negative electrode according to claim 1 ; a positive electrode comprising lithium cobalt oxide (LCO) or lithium nickel cobalt manganese oxide (NCM); an electrolyte having an ion conductivity of 6.5 mS/cm or more and containing a lithium salt at a concentration of 0.8-1.4 M; and a separator including a polyethylene porous film having a thickness of 3-15 μm; and optionally further comprising an inorganic coating layer disposed on the polyethylene porous film.

9 . The negative electrode for a lithium-ion secondary battery according to claim 1 , prepared by a manufacturing method comprising: preparing each of a first negative electrode slurry containing a lower layer negative electrode mixture and a second negative electrode slurry containing an upper layer negative electrode mixture; and sequentially or simultaneously applying the first negative electrode slurry and the second negative electrode slurry onto a negative electrode current collector, followed by drying.

10 . The negative electrode for a lithium-ion secondary battery according to claim 1 , wherein a content of the carbon coating layer in the lower layer is 1-4 wt % based on 100 wt % of the lower layer of the negative electrode active material layer.

11 . A negative electrode for a lithium-ion secondary battery, comprising a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector,

the lower layer and the upper layer include different compositions and formed by applying a slurry for the lower layer on the negative electrode current collector, and applying a slurry for the upper layer on the lower layer,

each of the lower layer and the upper layer independently includes a negative electrode mixture containing a negative electrode active material, a conductive material and a binder,

the negative electrode active material includes a negative electrode active material a and a negative electrode active material b,

the negative electrode active material a is an artificial graphite having a surface on which a carbonaceous material is coated,

the negative electrode active material b is an artificial graphite having a surface on which the carbonaceous material is not coated, and the negative electrode active material b is not heat treated with a carbon precursor material,

the upper layer has a higher content of the negative electrode active material a than a content of the negative electrode active material a in the lower layer,

the carbonaceous material coated on the artificial graphite is a carbon coating layer, and

the artificial graphite of the negative electrode active material a has a specific surface area of 0.5-0.9 m 2 /g.

12 . The negative electrode for a lithium-ion secondary battery according to claim 11 , wherein each of the artificial graphite of the negative electrode active material a and the artificial graphite of the negative electrode active material b independently has a degree of orientation, which is a ratio of I 110 to I 004 of particles of the artificial graphite of 3-25.

13 . The negative electrode for a lithium-ion secondary battery according to claim 11 , wherein each of the artificial graphite of the negative electrode active material a and the artificial graphite of the negative electrode active material b independently has a degree of orientation, which is a ratio of I 110 to I 004 of particles of the artificial graphite, of 12-25.

14 . The negative electrode for a lithium-ion secondary battery according to claim 11 , wherein the artificial graphite of the negative electrode active material b has a specific surface area of 0.5-5 m 2 /g.

15 . The negative electrode for a lithium-ion secondary battery according to claim 11 , wherein the carbonaceous material comprises a low-crystallinity carbonaceous material and/or an amorphous carbonaceous material.