Weak-Water-Coordination Electrolyte to Stabilize Zinc Anode Interface for Aqueous Zinc Ion Batteries

The performance of zinc-ion batteries is severely hindered by the uncontrolled growth of dendrites and the severe side reactions on the zinc anode interface. To address these challenges, a weak-water-coordination electrolyte is realized in a peptone-ZnSO4-based electrolyte to simultaneously regulate the solvation structure and the interfacial environment. The peptone molecules have stronger interaction with Zn2+ ions than with water molecules, making them more prone to coordinate with Zn2+ ions and then reducing the active water in the solvated sheath. Meantime, the peptone molecules selectively adsorb on the Zn metal surface, and then are reduced to form a stable solid-electrolyte interface layer that can facilitate uniform and dense Zn deposition to inhabit the dendritic growth. Consequently, the Zn||Zn symmetric cell can exhibit exceptional cycling performance over 3200 h at 1.0 mA cm-2/1.0 mAh cm-2 in the peptone-ZnSO4-based electrolyte. Moreover, when coupled with a Na2V6O16 center dot 3H2O cathode, the cell exhibits a long lifespan of 3000 cycles and maintains a high capacity retention rate of 84.3% at 5.0 A g-1. This study presents an effective approach for enabling simultaneous regulation of the solvation structure and interfacial environment to design a highly reversible Zn anode. A weak-water-coordination electrolyte based on a peptone-ZnSO4-based electrolyte is designed to modulate the solvation structure of Zn2+ ions and interfacial environment. The peptone molecules can solvate with Zn2+ ions and eliminate the water molecules to decrease the water activity. Meanwhile, the peptone molecules selectively adsorb on the Zn metal surface, and then are reduced, forming a stable solid-electrolyte interface layer to enable uniform and dense Zn deposition.image