Composite binder for silicon electrodes in lithium secondary batteries, manufacturing method thereof, and silicon electrodes for lithium secondary batteries using the same

Composite binder for furan-modified silicon anodes using Diels-Alder reaction-bonded carbon materials

This technology is a composite binder that connects water-soluble polymers, such as PAA and CMC, with furan-group-functionalized polymer complexes to carbon materials containing carbon-carbon pi bonds, like graphene and CNTs, via a Diels-Alder reaction. By combining a hydrophilic polymer backbone with hydrophobic carbon materials, it suppresses the expansion of silicon active materials while ensuring uniform dispersion of conductive additives.

Silicon anodes have historically faced issues with structural collapse due to significant volume changes during charge and discharge cycles. Traditional methods of adding dispersants to improve conductive additive distribution often reduced electrical conductivity and energy density when used in excess, while modifying carbon black typically led to unavoidable degradation in conductivity.

This technology is configured to chemically bond furan-functionalized water-soluble polymers with carbon materials at a weight ratio of 9:1 to 7:3 by heating in ultrapure water at 70–90°C to induce a Diels-Alder reaction. The bonded carbon materials capture and uniformly distribute conductive additives through pi-pi interactions, while the elasticity of the polymer physically constrains silicon expansion. Applicable to high-silicon content anodes, silicon-graphite composite anodes, and aqueous electrode slurry processes, it maintains both the conductive network and electrode structure without the need for separate dispersants.

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Key Features:

• A polymer composite forming the backbone of the composite binder, including a polymer and furan groups bonded to said polymer
• A carbon material containing carbon-carbon pi bonds, blended with the polymer composite at a weight ratio of 9:1 to 7:3
• A chemical bond between the polymer composite and the carbon material, formed via a Diels-Alder reaction conducted at a temperature range of 70°C to 90°C
• A process of obtaining the polymer composite by adding a furan-containing solution to an aqueous polymer solution, followed by stirring and drying

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This invention was developed with support from the Ministry of Science and ICT for the development of user-customized, high-performance, and high-safety stretchable aqueous zinc-ion secondary batteries using stretchable hybrid electrode networks.

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