EP-4739431-A2 - CATALYST-EMBEDDED MESOPOROUS CARBON CRYOGELS FOR ENERGY STORAGE

Abstract

A method for fabricating carbon cryogel exhibiting high surface area, an increased mesopore ratio, and cost-efficiency, utilizing biomass-derived, low-cost tannin and formaldehyde. Furthermore, this method incorporates calcium salt as a catalyst, a deviation from the widely used sodium carbonate. The resulting carbon cryogel possesses high surface area, an enhanced mesopore ratio, and improved sulfur loading capacity, rendering them ideal sulfur hosts for Li-S batteries. The present method disclosed herein constitutes a significant improvement over the existing state-of-the-art carbon cryogel for Li-S batteries, with potential implications for the progression of high-performance, cost- effective Li-S batteries.

Inventors

• YANG, JUNBING

Assignees

• XBM USA LLC

Dates

Publication Date

20260513

Application Date

20240708

Claims (20)

1. 1. A method for producing a catalyst-embedded mesoporous carbon cryogel, comprising: preparing a sol-gel solution that includes a biomass-derived polyphenolic precursor, a crosslinking agent, a catalyst, and a surfactant in a solvent; aging the sol-gel solution to form a gel; freezing the gel to form an organic cryogel; carbonizing the organic cryogel in the presence of an inert gas to prepare a carbon cryogel having a first number of mesopores; and activating the carbonized cryogel in the presence of an oxidative gas to prepare an activated carbon cryogel having a second number of mesopores in the carbon cryogel, the second number of mesopores for the activated carbon cryogel being larger than the first number of mesopores in the carbonized cryogel.
2. 2. The method of claim 1, further comprising freeze-drying the gel to form the organic cryogel.
3. 3. The method of claim 1, wherein the oxidative gas includes CO2, water steam, ozone, or combinations thereof.
4. 4. The method of claim 1, further comprising: treating the activated carbon cryogel in an acidic or alkaline solution to partially remove the catalyst particles, thereby increasing the pore volume of the activated carbon cryogel; rinsing the treated cryogel with distilled water to remove any residual acid or alkaline; and subsequently drying the cryogel.
5. 5. The method of claim 1, further comprising treating the catalyst-embedded carbon cryogel in a carbide-inhibiting gas at a temperature between 800°C and 1300°C to increase its electric conductivity, with the carbide-inhibiting agent minimizing the formation of metal carbides.
6. 6. The method of claim 1, wherein the activated carbon cryogel possesses mesopores with diameters between 2 and 50 nanometers, and macropores with diameters between 50 and 300 nanometers.
7. 7. The method of claim 1, wherein the activated carbon cryogel exhibits a specific surface area between 300 to 1500 m 2 /g , and a total pore volume between 0.3 to 3.0 cc/g.
8. 8. The method of claim 1, wherein nanoparticles are uniformly distributed and embedded within the pores of the activated carbon cryogel, and the nanoparticles have a diameter between 2nm to 100 nm.
9. 9. The method of claim 1, wherein the activated carbon cryogel exhibits a catalyst loading between 0.1 to 10 wt.%, and preferably within the range of 2 to 5 wt.%.
10. 10. The method of claim 1, wherein the Biomass-derived polyphenolic precursor comprise one or more of tannin and lignin, the one or more of tannin and lignin from renewable biomass sources such as plants or agricultural residues.
11. 11. The method of claim 1, wherein the Biomass-derived polyphenolic precursor are extracted from one or more of bark, wood, nutshells, and plant residues.
12. 12. The method of claim 1, wherein the Biomass-derived polyphenolic precursor are chemically modified to enhance their reactivity and suitability for the sol-gel process.
13. 13. The method of claim 1, wherein the Biomass-derived polyphenolic precursor are mixed with a suitable solvent to form the sol-gel solution, further enhancing their compatibility and processing characteristics.
14. 14. The method of claim 1 , wherein aging includes the use of ultrasound-assisted sol-gel synthesis to stimulate rapid gelation.
15. 15. The method of claim 1, wherein aging includes the user of microwave irradiation to induce faster radiation.
16. 16. The method of claim 1, wherein the crosslinking agent comprises formaldehyde and a biomass-derived crosslinking agent, selected from the group consisting of furfural, levulinic acid, glyoxal, and their derivatives.
17. 17. The method of claim 1, wherein the biomass-derived crosslinking agent is furfural.
18. 18. The method of claim 1, wherein the catalyst added to the aqueous solution to promote the sol-gel reaction and form a crosslinked gel network is selected from the group consisting of group consisting of sodium carbonate, calcium carbonate, calcium nitrate, ammonium hydroxide, boron trifluoride etherate, boric acid, zinc chloride, magnesium oxide, tetramethylammonium hydroxide, titanium oxide, cobalt sulfide, nickel nitrate, iron nitrate and molybdenum nitride.
19. 19. The method of claim 1, wherein the catalyst comprises calcium nitrate, which undergoes conversion into calcium oxide during the carbonization step and serves as a carbon gasification catalyst in the activation step.
20. 20. The method of claim 1, wherein the catalyst comprises nickel nitrate, which undergoes conversion into nickel oxide during the carbonization step and serves as a carbon gasification catalyst in the activation step.

Description

CATALYST-EMBEDDED MESOPOROUS CARBON CRYOGELS FOR ENERGY STORAGE CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application claims the priority benefit of U.S. provisional patent application 63/525,213, filed on July 6, 2023, titled “Catalyst-Embedded Mcsoporous Carbon Cryogels for Energy Storage,” the disclosure of which is incorporated herein by reference. BACKGROUND [0002] Lithium- sulfur (Li-S) batteries have gained considerable attention as a promising energy storage technology due to their high theoretical energy density, low cost, and abundance of sulfur. In Li-S batteries, electrochemical reactions occur between lithium and sulfur, where sulfur serves as the active material in the cathode. However, the practical application of Li-S batteries faces several challenges that limit their performance and commercial viability. [0003] One of the major issues with Li-S batteries is the dissolution and migration of intermediate lithium polysulfide species (LiiSx, where x is typically between 4 and 8) during cycling, commonly referred to as the lithium polysulfide shuttle phenomenon. These highly soluble lithium poly sulfides can diffuse through the electrolyte and reach the lithium anode, resulting in capacity loss, poor cycling stability, and rapid degradation of the battery performance over repeated charge-discharge cycles. [0004] Various approaches have been explored to mitigate the lithium polysulfide shuttle and improve the performance of Li-S batteries. One promising strategy involves the use of carbon materials as hosts for sulfur, aiming to confine the sulfur species and prevent their dissolution and migration. Carbon materials, such as carbon aerogels and carbon cryogels, offer high surface area, porosity, and electrical conductivity, making them suitable candidates for sulfur encapsulation in Li-S batteries. [0005] Resorcinol-formaldehyde (RF) carbon cryogel have been widely investigated as hosts for sulfur in Li-S batteries. The cryogel are typically synthesized through the sol-gel process using resorcinol and formaldehyde as precursors, followed by aging, freeze drying, and carbonization. RF carbon cryogel provides a three-dimensional porous structure with a high surface area, enabling efficient sulfur loading and accommodating the volume expansion of sulfur during cycling. However, the RF system is expensive and limits the scalability of the process, thus necessitating the development of alternative methods to produce carbon cryogel. [0006] Doping nanoparticles such as metal, metal oxide, sulfide and nitride into porous carbon has been proven to be an effective strategy for mitigating the lithium polysulfide shuttle phenomenon in lithium- sulfur (Li-S) batteries. The presence of these catalyst nanoparticles within the carbon host materials enhances the electrochemical reactions and prevents the migration of lithium polysulfides, thereby improving battery performance. [0007] However, it is important to ensure a uniform distribution of the catalyst nanoparticles throughout the carbon structure to maximize their catalytic effect. Traditional methods of catalyst loading onto porous carbon often result in non-uniform distribution, leading to sub-optimal catalyst utilization and performance degradation. Achieving a uniform catalyst distribution within the carbon host materials is crucial to fully leverage their catalytic capabilities and effectively mitigate the lithium polysulfide shuttle. [0008] Typical approaches for catalyst loading onto porous carbon often result in non- uniform distribution, leading to sub-optimal catalyst utilization and performance degradation. Achieving a uniform catalyst distribution throughout the carbon structure is crucial to maximize the catalytic effect on the electrochemical reactions and mitigate the lithium polysulfide shuttle. SUMMARY [0009] The present technology produces catalyst-embedded mesoporous carbon cryogels with improved porosity and sulfur loading capacity for lithium-sulfur batteries. The carbon cryogels can be fabricated using biomass-derived precursors, a crosslinking agent, a catalyst, a surfactant, and a solvent. The catalyst undergoes conversion into metal nanoparticles and serves as a carbon gasification catalyst during the activation process, resulting in the creation of large mesopores around them in the carbon cryogels. The resulting carbon cryogels exhibit high surface area, well-defined pore structure, and a uniform distribution of embedded catalyst nanoparticles. These materials address the limitations of Li-S batteries, offering enhanced battery performance and applications in energy storage systems. [0010] In some instances, the present technology implements a method for producing a catalyst-embedded mesoporous carbon cryogel. The method begins with preparing a solgel solution that includes a biomass-derived polyphenolic precursor, a crosslinking agent, a catalyst, and a surfactant in a solvent. The sol-gel solution is then a