# US 12,603,277 B2 · Negative electrode active material for lithium secondary battery and method of preparing the same

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- Number: US 12,603,277 B2
- Document ID: US12603277B2
- Status: Granted
- Kind: B2
- Application number: 17/725,338
- Filed: 2022-04-20
- Published: 2022-08-11
- Granted: 2026-04-14
- Earliest claimed: 2015-09-24
- Assignees: LG Energy Solution, Ltd.
- Applicants: LG Energy Solution, Ltd.
- Inventors: Hyun Chul Kim; Yong Ju Lee; Eun Kyung Kim
- Web page: https://patentgrep.com/patent/US12603277B2

## CPC

- H01M 4/366: {as layered products}
- B01J 13/04: by physical processes, e.g. drying, spraying
- B01J 13/20: After-treatment of capsule walls, e.g. hardening
- 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 4/36: Selection of substances as active materials, active masses, active liquids
- 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 4/587: for inserting or intercalating light metals
- 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
- Y02E 60/10: Energy storage using batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A negative electrode active material which includes a silicon-based composite represented by SiOa (0≤a<1), and a carbon coating layer distributed on a surface of the silicon-based composite, and which has a bimodal pore structure including nanopores and mesopores. In a lithium secondary battery including the negative electrode active material, an oxygen content in the silicon-based composite can be controlled to improve initial efficiency and capacity characteristics, and a specific surface area can also be controlled, and thus a side reaction with electrolyte can be reduced.

## Claims

### Claim 1

A method of preparing a negative electrode active material, comprising:
forming a carbon coating layer on a silicon-based precursor represented by SiOx (0<x≤2); and
thermally treating the silicon-based precursor on which the carbon coating layer is formed to prepare a silicon-based composite represented by SiOa (0<a<1) having a surface on which the carbon coating layer is distributed by removing impurities,
wherein the silicon-based composite has a bimodal pore structure including mesopores and macropores,
wherein the thermal treatment includes thermally reducing the silicon-based precursor with a metal reducing agent in an inert atmosphere,
wherein in the silicon-based composite, a ratio of crystalline silicon and crystalline silica contained therein is expressed as 1−(3/2):(a/2), and
wherein the silicon-based composite represented by SiOa (0<a<1) consists of crystalline silicon and crystalline silica, and no amorphous silicon is present.

### Claim 2 (depends on 1)

The method according to claim 1, wherein a content of the carbon coating layer is in a range of 1 wt % to 50 wt % of a total weight of the negative electrode active material.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the metal reducing agent includes one selected from the group consisting of Ti, Al, Mg, Ca, Be, Sr, Ba and a combination thereof.

### Claim 4 (depends on 1)

The method according to claim 1, wherein a molar ratio of the silicon-based precursor to the metal reducing agent is in a range of 1:0.001 to 1:1.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the thermal treatment is performed in a temperature range of 650° C. to 900° C.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the preparing of the silicon-based composite includes removing impurities using an acidic aqueous solution.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the impurities include one or more materials selected from the group consisting of a metal oxide, a metal silicide and a metal silicate, and the metal is one selected from the group consisting of Ti, Al, Mg, Ca, Be, Sr, Ba and a combination thereof.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the silicon-based composite has the bimodal pore structure formed entirely from an inner central portion to a surface portion of the silicon-based composite.

### Claim 9 (depends on 1)

The method according to claim 1, wherein a diameter of the mesopores is in a range of 2 nm to 50 nm.

### Claim 10 (depends on 1)

The method according to claim 1, wherein a diameter of the mesopores is in a range of 50 nm to 700 nm.

### Claim 11 (depends on 1)

The method according to claim 1, wherein a thickness of the carbon coating layer is in a range of 0.003 μm to 3.0 μm.

### Claim 12 (depends on 1)

The method according to claim 1, wherein a specific surface area of the negative electrode active material is in a range of 1 m2/g to 20 m2/g.