Integrating π-Conjugated and Flexible Alkyl Side Chains via P3HT Incorporation into PAA Binder for High-Performance Silicon Anodes

A functional composite binder (PAA-P3HT), composed of poly(acrylic acid) (PAA) and highly conductive poly(3-hexylthiophene) (P3HT), was rationally designed to address the electronic insulation of PAA and the instability of conventional conductive agents in silicon (Si) anodes. The resulting binder exhibits excellent electronic conductivity, efficient lithium-ion transport, and mechanical elasticity. A synergistic dual-conductive network formed by PAA-P3HT and Super P ensures continuous electron pathways and rapid ion diffusion, significantly enhancing the electrochemical performance of Si anodes. In addition, the flexible hexyl side chains of P3HT improve binder deformability, effectively accommodating Si volume changes, reducing local stress, and suppressing microcrack formation. Consequently, the Si anode using this binder achieves a high initial Coulombic efficiency of 86.72% and a specific capacity of 3530 mAh g–1 at 50 mA g–1. After 200 cycles, it retains a reversible capacity of 2351 mAh g–1, demonstrating excellent cycling stability. This work provides a promising binder design strategy for high-performance Si anodes and offers valuable insights into the development of advanced lithium-ion batteries.