A Carboxyl‐Rich 3D Cross‐Linked Polymer Binder for High‐Performance Silicon Anodes in Lithium‐Ion Batteries

A 3D cross-linked binder was developed by incorporating tannic acid into carboxyl-rich poly(methyl vinyl ether-alt-maleic acid). The resulting binder forms strong covalent bonds and reversible hydrogen bonds, effectively addressing silicon anode challenges by suppressing volume expansion and enhancing cycling stability.

The significant volume expansion and poor interfacial stability of silicon anodes pose major challenges for their commercial application in next-generation high-energy density lithium-ion batteries. Herein, a novel 3D cross-linked binder is developed by incorporating highly-branched tannic acid (TA) into poly(methyl vinyl ether-alt-maleic acid) (PMV-EMA) polymer for silicon anodes. The resulting binder forms strong covalent bonds and reversible hydrogen bonds via cross-link reaction of rich carboxyl and abundant hydroxyl groups, imparting the binder with enhanced self-healing properties and excellent adhesion to the silicon anode. As a result, the PMV-EMA-TA-based silicon electrode retains an impressive reversible specific capacity of 1863.0 mA h g⁻¹ at 1 A g⁻¹ after 280 cycles. Additionally, full cells using a nanosized Si anode and NCM811 cathode demonstrate good cycle performance. This work presents a promising strategy for advancing high-energy-density batteries by leveraging robust and networked polymeric binders that are both practical and cost-effective for scalable applications.

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