Copolymer, method for preparing the same, polymer binder for silicon anodes containing the same, silicon anode containing said polymer binder, and lithium-ion battery containing said silicon anode

High-Capacity Silicon Anode Binder Based on Diels-Alder Cross-Linked Self-Healing Copolymer

This technology synthesizes a 3D network copolymer with excellent self-healing properties and mechanical strength by using a Diels-Alder reaction to polymerize a polyacrylic acid backbone modified with furfurylamine and bismaleimide side chains to mitigate the volume expansion of silicon anodes.

Silicon anodes have historically faced issues with particle pulverization due to significant volume expansion and contraction during charge and discharge cycles. This leads to loss of electrical contact, unstable SEI layers, and electrode delamination, resulting in a rapid decline in battery life and capacity.

This technology uses a copolymer binder formed by the Diels-Alder reaction between furfurylamine-modified polyacrylic acid (PFM) and a bismaleimide (BMI) cross-linker. It self-heals damage caused by volume changes and maintains strong adhesion between silicon particles and the current collector through strong hydrogen bonding and a 3D network. Applicable to high-capacity silicon-rich anodes and fast-charging mobile batteries, it maintains over 92% coulombic efficiency for 200 cycles and delays electrode delamination.

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Key Features:

• Furfurylamine-modified polyacrylic acid backbone containing polyacrylic acid and furfurylamine in a molar ratio of 1:0.05 to 0.9
• Bismaleimide side chains bonded to the backbone side branches, acting as a cross-linker and included at 0.1–15 wt% relative to the backbone
• Step of adding a bismaleimide-based cross-linker to the furfurylamine-modified polyacrylic acid solution and cross-linking via Diels-Alder reaction to obtain the copolymer
• Silicon anode comprising a silicon-based active material and the copolymer-based polymer binder, exhibiting a coulombic efficiency of 92% or higher

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