Constructing a Coopetitive H2O-Poor Buffer Layer for Long-Cycle Stabilization of Zinc-Ion Batteries

Aqueous zinc-ion battery anodes face corrosion and the hydrogen evolution reaction, causing the Zn anode to grow dendrites and die after piercing the diaphragm during the plating-stripping process. In this work, Carboxylated Cellulose Nanofibers (CNF) were introduced into the ZnSO4 electrolyte. Owing to their inherent physicochemical properties and a high HOMO energy level, CNF molecules exhibit strong electron-donating capability and preferentially adsorb on the Zn surface. The adsorbed CNF molecules dynamically occupy interfacial active sites, limiting direct contact between H2O molecules and the Zn anode and thereby forming a H2O-poor electric double layer (EDL) buffer layer. This adsorption-based interfacial regulation layer effectively suppresses hydrogen evolution, corrosion, and dendrite growth. Specifically, Zn anodes adsorbed by CNF molecules have high cycling stability (more than 3000 h at 5 mA cm-2 and 1 mAh cm-2). The Coulombic efficiency of the Zn||Cu half-cell was maintained at 99.41% after 1000 cycles, and the capacity retention of the Zn||ZnI2 full-cell was 96.8% after 2000 cycles at 4 C. Moreover, the 0.9 Ah Zn||ZnI2@Ti pouch cell (with 10 × 10 cm AC films) using 1 M ZnSO4@10% CNF electrolyte retained 56.9% specific capacity after 500 cycles, showing favorable performance.