# US 2025/0158031 A1 · Lithium secondary battery with improved safety

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- Number: US 2025/0158031 A1
- Document ID: US20250158031A1
- Status: Published application
- Kind: A1
- Application number: 18/729,492
- Filed: 2023-07-17
- Published: 2025-05-15
- Earliest claimed: 2022-07-21
- Assignees: LG Energy Solution, Ltd.
- Applicants: LG Energy Solution, Ltd.
- Inventors: Young Jun KO; Joo Hwan SUNG; Kyung Hwan JUNG
- Web page: https://patentgrep.com/patent/US20250158031A1

## CPC

- H01M 4/366: {as layered products}
- H01M 4/48: of inorganic oxides or hydroxides
- 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 4/133: Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/134: Electrodes based on metals, Si or alloys
- H01M 4/136: Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
- H01M 4/36: Selection of substances as active materials, active masses, active liquids
- H01M 4/362: {Composites}
- H01M 4/364: {as mixtures}
- H01M 4/38: of elements or alloys
- H01M 4/386: {Silicon or alloys based on silicon}
- H01M 4/483: {for non-aqueous cells (H01M4/485 takes precedence)}
- 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 4/58: of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M 4/5825: {Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines}
- H01M 4/583: Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/587: for inserting or intercalating light metals
- H01M 4/62: Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M 4/625: {Carbon or graphite}
- 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 2004/021: {Physical characteristics, e.g. porosity, surface area}
- H01M 2004/027: {Negative electrodes}
- 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

A negative electrode for a lithium secondary battery and a lithium secondary battery including the same, where the negative electrode i) has a high energy density by containing a silicon-based material as a negative electrode active material, and ii) having an individual mixture layer including a silicon-based material having a relatively low electrical conductivity at the outermost part of the negative electrode mixture layer of a multilayer structure, so that the amount of current may be lowered in the event of an internal short circuit and the amount of heat generation may be reduced.

## Claims

### Claim 1

A negative electrode for a lithium secondary battery, the negative electrode comprising:
a negative electrode current collector, and
a first negative electrode mixture layer to a nth negative electrode mixture layer (where n≥2) disposed at the negative electrode current collector,
wherein the first negative electrode mixture layer to n−1th negative electrode mixture layer comprises a first negative electrode active material including a carbon-based material and a second negative electrode active material including a silicon-based material,
wherein the nth negative electrode mixture layer comprises the second negative electrode active material including the silicon-based material.

### Claim 2 (depends on 1)

The negative electrode for a lithium secondary battery of claim 1, wherein a content or a content ratio of the second negative electrode active material increases in respective negative electrode mixture layer of the first negative electrode mixture layer to the n−1th negative electrode mixture layer positioned sequentially at the negative electrode current collector.

### Claim 3 (depends on 1)

The negative electrode for a lithium secondary battery of claim 1, wherein the carbon-based material comprises one or more selected from a group comprising soft carbon, hard carbon, natural graphite, artificial graphite, expanded graphite, non-graphitizable carbon carbon black, acetylene black, ketjen black, carbon nanotubes, fullerene, activated carbon, graphene, and carbon fiber.

### Claim 4 (depends on 1)

The negative electrode for a lithium secondary battery of claim 1, wherein the silicon-based material comprises one or more selected from a group comprising silicon (Si), silicon carbide (SiC), and silicon oxide (SiOq, where 0.8≤q≤2.5).

### Claim 5 (depends on 1)

The negative electrode for a lithium secondary battery of claim 1, wherein the second negative electrode active material is included in 1 to 20 wt % with respect to a total weight of negative electrode active material of a negative electrode mixture layer.

### Claim 6 (depends on 1)

The negative electrode for a lithium secondary battery of claim 1, wherein the second negative electrode active material has a sphericity of 0.5 to 1.0, and the sphericity decreases in respective negative electrode mixture layer of the first negative electrode mixture layer to the nth negative electrode mixture layer positioned sequentially at the negative electrode current collector.

### Claim 7 (depends on 1)

The negative electrode for a lithium secondary battery of claim 1, wherein a total thickness of a negative electrode mixture layer is 50 μm to 300 μm.

### Claim 8 (depends on 1)

The negative electrode for a lithium secondary battery of claim 1, wherein a thickness of the nth negative electrode mixture layer is from 5% to 30% of a total thickness of a positive electrode mixture layer of the lithium secondary battery.

### Claim 9 (depends on 1)

A lithium secondary battery comprising the negative electrode according to claim 1, a positive electrode, and a separator positioned between the negative electrode and positive electrode.

### Claim 10 (depends on 9)

The lithium secondary battery of claim 9, wherein the positive electrode comprises a positive electrode current collector and a first positive electrode mixture layer to a mth positive electrode mixture layer (where m≥2) disposed at the positive electrode current collector,
wherein the first positive electrode mixture layer to the mth positive electrode mixture layer comprise a first positive electrode active material comprising a lithium complex metal oxide represented by Formula 1 and a second positive electrode active material comprising an iron phosphate compound represented by Formula 2:
Lix[NiyCozMnwM1v]O2 [Formula 1]
LiFeaM21-aXO4 [Formula 2]
wherein, in Formula 1 and Formula 2,
M1 is one or more elements selected from a group comprising W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo,
x, y, z, w, and v are 1.0≤x≤1.30, 0.1≤y<1, 0≤z≤1, 0≤w≤1, and 0≤v≤0.1, respectively, where y+z+w+v=1,
M2 is one or more elements selected from a group comprising W, Cu, Fe, V, Cr, Co, Ni, Mn, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo,
X is one or more selected from the group consisting of P, Si, S, As, and Sb, and
a is 0≤a≤0.5.

### Claim 11 (depends on 10)

The lithium secondary battery of claim 10, wherein a content or a content ratio of the second positive electrode active material in each positive electrode mixture layer increases in respective positive electrode mixture layer of the first positive electrode mixture layer to the mth positive electrode mixture layer positioned sequentially at the positive electrode current collector.

### Claim 12 (depends on 10)

The lithium secondary battery of claim 10, wherein the second positive electrode active material is included in less than 10 wt % with respect to a total weight of positive electrode active material of a positive electrode mixture layer.

### Claim 13 (depends on 10)

The lithium secondary battery of claim 10, wherein a total thickness of a positive electrode mixture layer is 50 μm to 300 μm.

### Claim 14 (depends on 9)

A secondary battery module comprising the lithium secondary battery according to claim 9.