Function-Oriented Modular Molecular Design of a Chitin-Derived Self-Healable Binder for Promising Zinc Powder Anodes.

Abstract

Replacing zinc foil with Zn micropowders (ZnMPs) enhances manufacturing compatibility for Zn-metal batteries but imposes challenges like uncontrolled Zn deposition and accelerated structural degradation, typically resulting in a short cycle life of < 50 cycles. Herein, we synthesize a multifunctional bottle-brush polycationic binder based on naturally abundant and mechanically robust chitin, which enables exceptional long-term Zn plating/stripping reversibility, averaging 99.5% Coulombic efficiency over 300 cycles. The design rationales are experimentally validated as follows: diverse functional groups integrated onto the chitin backbone provide multiple supramolecular interactions ensuring ZnMP electrodes' spatial uniformity and structural robustness; Zn²⁺-carboxylate coordination simultaneously enhances the binder's mechanical strength (~1.2 MPa), toughness (~8.6 MJ m^-3) and ionic conductivity (an 87% increase, reaching 1.72 × 10^-5 S cm^- ¹) upon swelling; while synergistic dynamic electrostatic interactions and hydrogen bonding permit rapid self-recovery of the electrodes during cycling. This work underscores the promise of supramolecular engineering for binders targeting aggressive electrode chemistries.