Robust Polyurethane Binders Intensified by Hydrogen Bonding, a Dynamic S–S Bond, and Metal-Ion Coordination for Silicon Anodes AITranslate

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DOI：https://doi.org/10.1021/acsapm.3c02189

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Silicon (Si) anodes undergo severe volume expansion during charging and discharging, resulting in degradation of their electrochemical performance. Polymer binders are one of the most cost-effective ways to suppress the volume expansion of Si particles. In this paper, polyurethane (BFPU) containing conductive cycloalkane, a dynamic S–S bond, and multiple hydrogen bonds is synthesized. After that, polymeric cross-linked network binders with multiple functional bond groups are obtained by cross-linking BFPU and polydopamine (PDA) with metal ions like Zn2+, Fe3+, and Al3+ (PDA-M-BFPU; M = Zn, Fe, Al). The introduction of metal ions, hydrogen bonding, and a dynamic S–S bond network significantly improves the Li+ diffusion rate and mechanical strength, which effectively inhibits the volume expansion of the Si anode. With the addition of metal ions, the initial Coulombic efficiency (ICE) of half-cells increases from 76.5% to over 80%, especially for Si/PDA-Al-BFPU, which reaches 84.5%. Also, the capacity retention rate of Si/PDA-Al-BFPU is 76.8% after 200 cycles at 0.3 C. In addition, the full cell of NCM811//Si/PDA-Al-BFPU shows good cycle stability and rate performance. The robust BFPU binder intensified by hydrogen bonding, a dynamic S–S bond, and metal-ion coordination already exhibits great potential for application in Si anodes.