Graft copolymer, method for preparing the same, binder for silicon anodes comprising the same, silicon anode comprising said binder, and lithium-ion battery comprising said silicon anode

Silicon Anode Binder Grafted with Conductive Aniline-Based Side Chains on a Chitosan Backbone

This technology features a polymer binder created by graft-polymerizing highly conductive aniline-based polymers onto a chitosan backbone. By securing both mechanical strength and electrical conductivity, it suppresses the volume expansion of silicon anodes and maintains a stable electrical network.

Conventional silicon anode binders, such as PVdF, often fail to withstand the significant volume changes of silicon particles during charge and discharge cycles, leading to electrode structural collapse. Furthermore, they suffer from rapid capacity degradation as electrical contact with the current collector is lost.

This technology utilizes a graft copolymer binder, combining natural chitosan—which provides mechanical strength and adhesion—with conductive aniline-based polymers via radical polymerization. By introducing carboxyl groups and controlling weight ratios, the binder enhances bonding with silicon particles and improves electrochemical stability. Applicable to high-capacity, silicon-rich anodes and eco-friendly materials derived from crustacean byproducts, this solution reduces reliance on conductive additives while effectively delaying electrode structural collapse.

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Key Features:

• A graft copolymer consisting of a chitosan-containing backbone and aniline-based polymer side chains bonded to the backbone
• An aniline-based polymer having repeating units in which at least one of R1 to R4 is substituted with COOH
• A step of preparing a chitosan solution by dissolving chitosan in a 0.1 to 5 M HCl acidic solution at 70 to 200 °C
• A step of preparing a graft copolymer by adding aniline monomers and anthranilic acid monomers to the chitosan solution and polymerizing them in the presence of an initiator

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