A Rigidity-Flexibility Tunable Polyimide Binder via Hydrogen-Bonding Network for High-Rate Cycling of Silicon Anodes in Lithium-Ion Batteries

Authors:
  • ZHZihao Huang
    Zihao Huang
  • JLJiashu Lin
    Jiashu Lin
  • HHHaitao Huang
    Haitao Huang
  • YSYinghua Sha
    Yinghua Sha
  • ZLZunchu Liu
    Zunchu Liu
  • HZHuan Zhang
    Huan Zhang
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Abstract
To address the severe structural degradation of silicon anodes induced by substantial volume expansion during cycling, this study designs a high-performance polyimide binder via a synergistic hydrogen-bond network and rigidity-flexibility modulation. The rigid amide-rich framework ensures mechanical robustness and strong interfacial adhesion to silicon particles through hydrogen bonding. Simultaneously, incorporated flexible polyether segments improve structural compliance to buffer volume strain and boost ionic conductivity via enhanced electrolyte wettability. Comprehensive characterization, including in situ temperature-dependent FTIR and XPS analyses, confirms the formation of a resilient internal hydrogen-bond network and strong binder-Si interfacial interactions. This dual strategy endows the optimized PI-5% binder with exceptional properties: ultrahigh adhesion (9.35 N/cm), low electrolyte swelling (5.80%), and enhanced ionic conductivity (0.29 mS·cm⁻¹). These features collectively maintain electrode integrity and stabilize the SEI, leading to outstanding electrochemical performance: an initial Coulombic efficiency of 87.94%, a reversible capacity of 1076.9 mAh·g⁻¹ after 550 cycles at 3.0 A·g⁻¹, and 86.44% capacity retention (2120.7 mAh·g⁻¹) at 1.2 A·g⁻¹, significantly surpassing conventional CMC-based electrodes. This study provides an effective strategy for designing high-performance polyimide binders by elucidating the synergistic interplay between hydrogen-bonding networks and rigidity-flexibility balance, providing theoretical guidance for the development of advanced binders for silicon-based lithium-ion batteries.

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