Hydrogen bond-induced elastic polyzwitterion electrolytes constructed by mussel-inspired autopolymerization for zinc-ion battery

Abstract

Aqueous zinc-ion batteries (ZIBs) have attracted much interest to realize safe rechargeable batteries with high safety and high energy density. However, it is still challenging to address dendrite growth and parasitic reactions in zinc anodes. We propose herein the design concept of hydrogen bond-induced elastic polyzwitterion electrolytes with zincophilic groups for achieving robust ZIBs. Mussel-inspired autopolymerization has been developed to construct the polyzwitterion electrolytes at room temperature by inducing electron density delocalization at α-position of C=C bond in zwitterion monomer by Zn²⁺. Specifically, the zwitterionic functional groups construct ion transport channels, and the unique–NH–and SO₃⁻ groups co-compete with H₂O for coordination with Zn²⁺ and promote the desolvation of hydrated Zn²⁺, thus achieving a high room temperature ionic conductivity (6.7 mS cm⁻¹) and an increased Zn²⁺ migration number (0.65) for the polyzwitterion electrolytes. In addition, various interactions such as hydrogen bonding and electrostatic interactions between electrolyte ions and zwitterionic groups impart high stretchability and strength to the polyzwitterion electrolytes, which, combined with SO₃⁻ philic (002) crystallographic properties, effectively inhibit the growth of zinc dendrites. As a result, rigid/wearable solid-state ZIBs exhibit excellent cycling and C-rate performances. We believe that the strategy of constructing polyzwitterionic electrolytes with zincophilic groups and ion transport channels opens up a new direction in polymer electrolyte engineering towards safe and high energy batteries.