Constructing a Coopetitive H ₂ O-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 ZnSO 4 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 H 2 O molecules and the Zn anode and thereby forming a H 2 O-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||ZnI 2 full-cell was 96.8% after 2000 cycles at 4 C. Moreover, the 0.9 Ah Zn||ZnI 2 @Ti pouch cell (with 10 × 10 cm AC films) using 1 M ZnSO 4 @10% CNF electrolyte retained 56.9% specific capacity after 500 cycles, showing favorable performance.