Mutual-activation effect and hydrogen-bond reconfiguration enabling fast ion-transport and self-healing artificial SEI for ultra-stable zinc anodes

Artificial solid electrolyte interphase (SEI) represents a promising strategy for stabilizing Zn electrodes by suppressing dendrite formation and parasitic reactions. However, conventional SEI designs suffer from sluggish Zn²⁺ transport kinetics and mechanical instability during cycling. Herein, we construct a thin chitosan@alginate (CS@SA, ∼1.5 μm) bilayer SEI on Zn electrodes via electrodeposition. Mutually activated functional groups (–COOH in outer SA and –NH₂ in inner CS) synergistically (1) facilitate the desolvation of [Zn(H₂O)₆]²⁺, (2) block reactive H₂O contact with the Zn surface, and (3) establish polymer-chain-accelerated Zn²⁺ transport pathways. Hydrogen-bond reconfiguration endows the CS@SA bilayer with in-situ self-healing and anti-detachment features, dynamically maintaining interfacial integrity. These merits simultaneously enhance the Zn electrode stability and Zn²⁺ migration kinetics. Consequently, the Zn@CS@SA electrode demonstrates a high average Coulombic efficiency (CE) of 99.74% over 1000 cycles at 2 mA cm⁻² and 1 mAh cm⁻² in the asymmetric cell. The Zn@CS@SA//MnO₂ demonstrates a four-fold capacity of Zn//MnO₂ after 1000 cycles at 2 A g⁻¹.