Coupled ion desolvation and nucleation control for stable zinc anodes enabled by a polyoxometalate-crosslinked nanocellulose separator

Abstract

Aqueous zinc batteries (AZBs) are attractive for their low cost and intrinsic safety, yet their practical application is hindered by the poor electrochemical cycling stability of zinc metal anodes in aqueous electrolytes. Herein, we report a polyoxometalate-crosslinked nanocellulose (PC) separator engineered to regulate interfacial ion transport and stabilize zinc plating/stripping processes. The PC separator features robust, anti-swelling nanochannels that disrupt the hydrogen-bond network of water, inducing partial Zn²⁺ desolvation and reducing the solvation sheath. This structural confinement lowers the energy barrier for Zn²⁺ migration, enhancing ionic conductivity and accelerating charge-transfer kinetics at the electrode–electrolyte interface. Simultaneously, the uniform nanochannels spatially homogenize Zn²⁺ flux, promoting uniform nucleation and refining the crystalline morphology of deposited zinc, effectively suppressing dendrite formation. Electrochemical evaluations demonstrate markedly improved coulombic efficiency and extended cycling durability compared to conventional cellulose and glass fiber separators. This work provides mechanistic insight into the synergistic interplay between separator structure and electrolyte dynamics, offering a viable separator strategy to stabilize zinc anodes and advance the practical application of AZBs.