Modulating Dynamic Deprotonation Evolution via Sacrificial Solvation Structure to Mitigate Zinc Electrochemical Corrosion and Cathodic Structure Deterioration for High-Stable Zinc-Vanadium Batteries.

Abstract

Compared to the free water molecules induced chemical corrosion, the electrochemical corrosion arising from the structured water elicits more pronounced zinc anode degradation, result in the limited cycle lifespan, especially at low current densities. However, the interfacial degradation mechanism remains inadequately resolved. Herein, for the inhibition of proton-induced side reactions, a lean-water polymer electrolyte is developed through the chelation of carboxymethyl chitosan (CCS) with Zn2+ ions. In accordance with Fajans' rules, CCS with highly polar carboxylate and strong electron-withdrawing amino groups exhibits enhanced ionic polarizability, which forms distinctive solvation structures with reduced deprotonation energy. Such solvation structures demonstrate competitive advantages in interfacial deprotonation dynamics and minimize proton release to suppress electrochemical corrosion via sacrificial protection. Furthermore, the crosslinked framework induced by molecular crowding restricts free water mobility, thereby alleviating zinc chemical corrosion and cathodic structure deterioration. By employing advanced MRI technology, the movement trajectories of water molecules and the dynamic deprotonation evolution process are directly visualized. Therefore, the cyclically rested Zn symmetric cell impressively operates 4000 h at low current density of 0.1 mA cm-2. Additionally, the Zn||NH4VO full cell exhibits 81% capacity retention after cycling over 1000 cycles at 1 A g-1, while the aqueous electrolyte only maintains 31%.