# US 10,770,727 B2 · Cathode active material for lithium-sulfur battery, comprising metal sulfide nanoparticles, and method for producing same

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- Number: US 10,770,727 B2
- Document ID: US10770727B2
- Status: Granted
- Kind: B2
- Application number: 16/308,316
- Filed: 2017-11-28
- Published: 2019-08-29
- Granted: 2020-09-08
- Earliest claimed: 2016-11-28
- Assignees: LG Chem, Ltd.
- Applicants: LG Chem, Ltd.
- Inventors: Dongwook Lee; Jongwook Jung; Kwonnam Sohn; Doo Kyung Yang; Gyo Hyun Hwang
- Web page: https://patentgrep.com/patent/US10770727B2

## CPC

- H01M 4/5815: {Sulfides}
- C01B 17/22: Alkali metal sulfides or polysulfides
- C01B 17/42: Sulfides or polysulfides of magnesium, calcium, strontium, or barium
- C01B 32/70: Compounds containing carbon and sulfur, e.g. thiophosgene
- H01M 4/131: Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
- H01M 4/362: {Composites}
- H01M 4/38: of elements or alloys
- H01M 4/583: Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 10/052: Li-accumulators
- H01M 2004/028: {Positive electrodes}
- Y02E 60/10: Energy storage using batteries
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A positive electrode active material for a lithium-sulfur battery, and more particularly, to a positive electrode active material for a lithium-sulfur battery including metal sulfide nanoparticles and a preparation method thereof. The metal sulfide nanoparticles with large specific surface area applied to the positive electrode active material for the lithium-sulfur battery according to the present invention acts as a redox mediator during charging and discharging of the lithium-sulfur battery, thereby reducing the shuttle response by not only inhibiting the formation itself of polysulfides with elution properties, but also, even if polysulfides are eluted, adsorbing them and thus preventing them from diffusing into the electrolyte solution, and thus the capacity and life characteristics of the lithium-sulfur battery can be improved.

## Claims

### Claim 1

A positive electrode active material for a lithium-sulfur battery, which comprises:
a sulfur/carbon composite; and
metal sulfide nanoparticles,
wherein the sulfur/carbon composite comprises sulfur particles supported on a porous carbon-based material, and
further wherein the metal sulfide nanoparticles are compounds represented by MxSy, wherein
x and y are integers that satisfy 0<x≤5 and 0<y≤5 respectively, and
M is at least one metal selected from the group consisting of cobalt (Co), molybdenum (Mo), titanium (Ti), nickel (Ni), copper (Cu), iron (Fe), cadmium (Cd), lead (Pb), manganese (Mn), antimony (Sb), arsenic (As), silver (Ag) and mercury (Hg).

### Claim 2 (depends on 1)

The positive electrode active material for the lithium-sulfur battery according to claim 1, wherein an average particle diameter of the metal sulfide nanoparticles is 0.1 to 200 nm.

### Claim 3 (depends on 1)

The positive electrode active material for the lithium-sulfur battery according to claim 1, wherein the metal sulfide nanoparticles are included in an amount of 1 to 20% by weight based on the total weight of the positive electrode active material.

### Claim 4 (depends on 1)

A preparation method of the positive electrode active material for the lithium-sulfur battery according to claim 1, which is prepared by
mixing the metal sulfide nanoparticles with the sulfur/carbon composite, wherein the preparation method of the metal sulfide nanoparticles comprises the following steps of:
i) preparing a sulfur precursor solution and a metal precursor solution;
ii) mixing the sulfur precursor solution and the metal precursor solution;
iii) reacting the mixed solution of ii) at 50 to 100° C. for 5 to 24 hours;
iv) washing and purifying the solution resulting from iii); and
v) drying.

### Claim 5 (depends on 4)

The preparation method of the positive electrode active material for the lithium-sulfur battery according to claim 4, wherein the sulfur precursor solution is a solution in which at least one compound selected from the group consisting of thioacetamide (TAA), thiourea, and sodium sulfide (Na2S) is dissolved in a solvent.

### Claim 6 (depends on 4)

The preparation method of the positive electrode active material for the lithium-sulfur battery according to claim 4, wherein the sulfur precursor solution contains a surfactant.

### Claim 7 (depends on 4)

The preparation method of the positive electrode active material for the lithium-sulfur battery according to claim 4, wherein the metal precursor solution is a solution including at least one compound selected from the group consisting of acetate, hydroxide, nitrate, nitride, sulfate, sulfide, alkoxide and halide, and which metal precursor solution contains at least one selected from the group consisting of cobalt (Co), molybdenum (Mo), titanium (Ti), nickel (Ni), copper (Cu), iron (Fe), cadmium (Cd), lead (Pb), manganese (Mn), antimony (Sb), arsenic (As), silver (Ag) and mercury (Hg).

### Claim 8 (depends on 1)

A lithium-sulfur battery, comprising:
a positive electrode;
a negative electrode; and
electrolyte,
wherein the positive electrode comprises the positive electrode active material according to claim 1.

### Claim 9 (depends on 1)

The positive electrode active material for the lithium-sulfur battery according to claim 1, wherein the metal sulfide nanoparticles are supported on the porous carbon-based material such that the metal sulfide nanoparticles are located on an interface between the porous carbon-based material and the sulfur particles.

### Claim 10 (depends on 1)

The positive electrode active material for the lithium-sulfur battery according to claim 1, wherein an average particle diameter of the metal sulfide nanoparticles is 10 to 100 nm.

### Claim 11 (depends on 1)

The positive electrode active material for the lithium-sulfur battery according to claim 1, wherein an average particle diameter of the metal sulfide nanoparticles is 20 to 50 nm.

### Claim 12 (depends on 1)

The positive electrode active material for the lithium-sulfur battery according to claim 1, wherein the metal sulfide nanoparticles are present in an amount of 5 to 10% by weight based on a total weight of the positive electrode active material.

### Claim 13 (depends on 1)

The positive electrode active material for the lithium-sulfur battery according to claim 1, wherein M is cobalt (Co).

### Claim 14 (depends on 13)

The positive electrode active material for the lithium-sulfur battery according to claim 13, wherein the metal sulfide nanoparticles comprise CoS2.

### Claim 15 (depends on 1)

The positive electrode active material for the lithium-sulfur battery according to claim 1, wherein sulfur particles and a porous carbon-based material are mixed in a weight ratio of 5:5 to 8:2 to prepare the sulfur/carbon composite.

### Claim 16 (depends on 1)

The positive electrode active material for the lithium-sulfur battery according to claim 1, wherein the metal sulfide nanoparticles are distributed on at least a portion of a surface of the sulfur/carbon composite.