The Polymer Society of Korea

Abstract

Silicon anodes offer very high theoretical capacity, but severe volume changes during cycling induce electrode cracking and unstable SEI growth, leading to rapid capacity decay. Thus, binders must combine strong Si adhesion, mechanical resilience, and efficient Li⁺ transport. Here, a single polymer platform was stepwise functionalized to optimize structure–property–performance. Carboxylic acids strengthened bonding to nano-Si but increased brittleness via excessive hydrogen bonding. Introducing mPEG (≈10%) mitigated this trade-off, delivering balanced mechanical properties (49.6 MPa, 25.5%), improved electrolyte affinity, and higher ionic conductivity. The optimized binder achieved 62.9% initial coulombic efficiency and 2495 mAh g⁻¹ reversible capacity, retaining 1680 mAh g⁻¹ after 250 cycles (72.8%). EIS/XPS/SEM confirm reduced interfacial resistance, a LiF-rich SEI, and suppressed volume expansion, supporting enhanced cycling stability.