CN-117957191-B - Positive electrode material for lithium-sulfur battery and lithium-sulfur battery comprising same

Abstract

The invention discloses a novel positive electrode active material used in a positive electrode of a lithium-sulfur battery. The positive electrode active material of the present invention comprises a) particles A comprising a first porous carbon material that is at least partially crystalline and catalyst particles deposited on the first porous carbon material, and B) particles B comprising a second porous carbon material that is at least partially crystalline and sulfur supported in the second porous carbon material, wherein the particles A and B have different morphologies.

Inventors

• Zheng Yaocan
• LI CHANGXUN
• Liang Shengpu

Assignees

• 株式会社LG新能源

Dates

Publication Date

20260508

Application Date

20230620

Priority Date

20220831

Claims (20)

1. 1. A positive electrode active material, comprising: a) Particles A comprising a first porous carbon material, at least part of which is crystalline, and catalyst particles deposited on the first porous carbon material, and B) Particles B comprising a second porous carbon material, at least part of which is crystalline, and sulfur supported in the second porous carbon material, Wherein the particles A and the particles B have different morphologies, Wherein the sphericity of the particles B is greater than the sphericity of the particles a; Wherein the sphericity is defined according to the following equation 1: [ formula 1] Wherein, ψ represents the sphericity, V p represents the volume of the particle, and A p represents the surface area of the particles.
2. 2. The positive electrode active material according to claim 1, wherein the first porous carbon material and/or the particles a are substantially free of sulfur.
3. 3. The positive electrode active material according to claim 1, wherein the second porous carbon material and/or the particles B are substantially free of catalyst particles.
4. 4. The positive electrode active material according to claim 1, wherein the catalyst particles are bonded to at least one of an outer surface or a surface inside pores of the first porous carbon material.
5. 5. The positive electrode active material according to claim 1, wherein a weight ratio of the second porous carbon material to the sulfur is 10:90 to 90:10.
6. 6. The positive electrode active material according to claim 1, wherein the sulfur is contained at least one position in an outer surface or a surface inside pores of the second porous carbon material.
7. 7. The positive electrode active material according to claim 1, wherein the sulfur comprises inorganic sulfur S 8 , lithium sulfide Li 2 S, lithium polysulfide Li 2 Sx, wherein 2≤x≤8, disulfide compounds, or a mixture thereof.
8. 8. The positive electrode active material according to claim 1, wherein, The particles A have a broccoli-like shape, a cauliflower-like shape or a spike-like shape, The particles B have a potato-like shape, a spherical shape or an elliptical shape.
9. 9. The positive electrode active material according to claim 1, wherein, The particles a have a size of 10 μm to 100 μm, The particles B have a size of 10 μm to 100. Mu.m.
10. 10. The positive electrode active material according to claim 1, wherein 50% or more of the particles a are present on the surface of the particles B.
11. 11. The positive electrode active material according to claim 1, wherein a surface of at least a part of the particles B is covered with the particles a, and Wherein the area of the particle B covered by the particle a is 20% to 50% of the entire outer area of the particle B.
12. 12. The positive electrode active material according to claim 1, wherein a surface of at least a part of the particles B is covered with the particles a, and Wherein the area of the particle B covered by the particle a is 20% to 90% of the entire outer area of the particle B.
13. 13. The positive electrode active material according to claim 1, wherein a weight ratio of the particles a to the particles B is 50:50 to 1:99.
14. 14. The positive electrode active material according to claim 1, wherein the porosity of the particles a is greater than the porosity of the particles B.
15. 15. The positive electrode active material according to claim 1, wherein the specific surface area of the particle a is larger than the specific surface area of the particle B.
16. 16. The positive electrode active material according to claim 1, wherein the particle a and the particle B are in contact with each other at least one position where the catalyst particle contained in the particle a exists.
17. 17. The positive electrode active material according to claim 1, wherein the particles a are anchored on the surface of the particles B by the catalyst particles.
18. 18. The positive electrode active material according to claim 1, wherein the particle a is fused with the particle B.
19. 19. The positive electrode active material according to claim 1, wherein the particles a fill gaps between the particles B.
20. 20. The positive electrode active material according to claim 1, wherein the positive electrode active material is in a fully charged state.

Description

Positive electrode material for lithium-sulfur battery and lithium-sulfur battery comprising same Technical Field The invention relates to a positive electrode material for a lithium-sulfur battery and a lithium-sulfur battery comprising the same. The present application claims priority from korean patent application No. 10-2022-0110283, filed on 31 at 8 and 2022, korean patent application No. 10-2022-0110385, filed on 31 at 8 and 2022, korean patent application No. 10-2022-0187899, filed on 28 at 12 and 2023, korean patent application No. 10-2023-0025408, filed on 24 at 2023, and korean patent application No. 10-2023-0042283, filed on 30at 3 and 2023, the disclosures of which are incorporated herein by reference. Background Lithium-sulfur batteries are battery systems that use a sulfur-based material having a sulfur-sulfur (S-S) bond for the positive electrode active material and metallic lithium for the negative electrode active material. Sulfur, which is a main component of the positive electrode active material, is abundant in nature and can be widely present worldwide, and is nontoxic and has a low atomic weight. Because secondary batteries are widely used in applications including Electric Vehicles (EV) and Energy Storage Systems (ESS), lithium-sulfur batteries that theoretically have a higher energy storage density per unit weight (2600 Wh/kg) than lithium-ion secondary batteries that have a lower energy storage density per unit weight (250 Wh/kg) are of interest. During discharge, the lithium sulfur battery undergoes oxidation at the negative electrode active material lithium by releasing electrons to lithium cations and undergoes reduction at the positive electrode active material sulfur-based material by accepting electrons. Through the reduction reaction, the sulfur-based material is converted into a sulfur anion through an S-S bond that accepts two electrons. Lithium cations generated by the oxidation reaction of lithium migrate to the positive electrode via the electrolyte and combine with sulfur anions generated by the reduction reaction of the sulfur-based compound to form a salt. Specifically, sulfur before discharge has a ring-shaped S 8 structure, and it is converted into lithium polysulfide (Li 2 Sx) by a reduction reaction and is completely reduced to lithium sulfide (Li 2 S). Since sulfur used in the positive electrode active material is non-conductive, electrons generated by the electrochemical reaction cannot move, and elution of polysulfide (LiSx) occurs during charge and discharge and low conductivity of sulfur and lithium sulfide slows down kinetics of the electrochemical reaction, which may deteriorate battery life characteristics and rate characteristics. In this case, in recent years, research has been conducted to utilize platinum (Pt) mainly used as an electrochemical catalyst to improve kinetics of oxidation and reduction reactions of sulfur during charge and discharge of a lithium sulfur secondary battery, thereby improving performance of the lithium sulfur secondary battery. However, since a noble metal catalyst such as platinum is expensive, high cost is an obstacle to commercialization, and there is a risk of poisoning due to oxidation and reduction reactions of sulfur during charge and discharge, so that it is not easy to use as a positive electrode material of a lithium-sulfur secondary battery. Therefore, there is a need to develop a technique of improving the kinetics of electrochemical reaction during charge and discharge of a lithium-sulfur secondary battery and a cathode material that can be commercialized with cost efficiency. Disclosure of Invention Technical problem The present invention aims to provide a novel positive electrode active material for use in a positive electrode of a lithium-sulfur battery. Technical proposal In order to solve the above-described problems, according to one aspect of the present invention, there is provided a positive electrode active material of the following embodiment. The positive electrode active material according to the first embodiment comprises a) particles a comprising a first porous carbon material that is at least partially crystalline and catalyst particles deposited on the first porous carbon material, and B) particles B comprising a second porous carbon material that is at least partially crystalline and sulfur supported in the second porous carbon material, wherein the particles a and B have different morphologies. According to the second embodiment, in the first embodiment, the sphericity of the particle B may be greater than that of the particle a, and the sphericity may be defined according to the following formula 1: [ formula 1] Where ψ represents sphericity, V p represents the volume of the particle, and a p represents the surface area of the particle. According to a third embodiment, in the first or second embodiment, 50% or more of the particles a may be present on the surface of the particles B. According t