Bifunctional gel coating for stabilizing zinc metal anodes in aqueous zinc-ion batteries

Abstract

Currently, the zinc anode faces significant challenges such as dendrite growth, corrosion, and hydrogen evolution, which severely limit the practical applications of aqueous zinc-ion batteries. To address these issues, this study designed a zinc anode (denoted as CG@Zn) coated with a gel composed of carboxymethyl cellulose sodium (CMC) and glucose. This coating featured dual functionalities: it regulated the directional transport of Zn²⁺ ions and constrained the electrochemical activity of interfacial water molecules, effectively inhibiting the growth of zinc dendrites and significantly reducing the occurrence of corrosion and hydrogen evolution side reactions. Benefiting from these advantages, CG@Zn exhibited excellent electrochemical performance. Under testing conditions of 5 mA cm⁻²/1 mAh cm⁻², the symmetric battery assembled with CG@Zn demonstrated over 1000 h of stable cycling, achieving a cycle life five times that of bare zinc electrodes. Furthermore, the full cell configuration of CG@Zn//NaV₃O₈·1.5H₂O with a matching zinc sulfate electrolyte maintained a capacity retention of 67.1 % after 15,000 cycles at 10 A g⁻¹, significantly outperforming the rapid capacity decay observed in bare zinc batteries under the same conditions. Therefore, this study successfully developed an effective bifunctional gel coating for zinc anodes using CMC and glucose, paving the way for the development of safe and eco-friendly aqueous zinc-ion batteries.