A Multifunctional Binder for Current-Collector-Free Zn Powder Anodes

Abstract

Compared with commonly used Zn foil anodes, Zn powder (ZP) anodes offer superior versatility and processability. However, in aqueous electrolytes, dendrite growth and side reactions, such as corrosion and hydrogen evolution, become more severe in ZP anodes than those in Zn foil anodes because of the rough surfaces and high surface areas of ZP, leading to poor reversibility and limitations in high-loading mass cathodes. In this study, a diisocyanate-polytetrahydrofuran-dihydrazide polymer (DDP) binder is developed, inspired by protein structures. The strong Zn²⁺ adsorption capability of the binder effectively regulates Zn²⁺ flux, while its unique hydrogen-bond arrays facilitate the formation of a free-standing ZP anode and inhibit side reactions. The binder exhibits superior mechanical performance, providing ZP electrodes with excellent resistance to various mechanical stresses, including tensile, nanoindentation, scratch, and dynamic bending tests. ZP symmetric cells achieve stable cycling at capacities of 2 and 5 mAh cm⁻². In addition, DDP functions as an iodine cathode, effectively mitigating the polyiodide shuttle effect. The fabricated ZP/DDP||I₂/DDP full cells demonstrate an excellent rate capability and cycling stability, even under a high-loading conditions. This study presents a novel approach for preparing stable ZP anodes and iodine cathodes, offering a promising strategy for large-scale applications.