Reconstructing anode/electrolyte interface and solvation structure towards high stable zinc anode

Abstract

The dendrite growth and side-reactions at unstable anode/electrolyte interface severely impair the electrochemical performance of aqueous zinc-ion battery. Herein, guided by the metal-coordination chemistry, a multifunctional electrolyte additive, sulfolane (SL), is introduced into aqueous ZnSO4 electrolyte to achieve uniform Zn deposition for highly stable and reversible zinc-ion batteries. Experimental results and theoretical calculations prove that the SL molecules can simultanously modulate Zn2+ solvation structure and anode/electrolyte interface. The electrolyte engineering is capable of modulating the primary solvation structure through expelling some active water to mitigate common parasitic reaction. Concomitantly, SL molecules are inclined to adsorb on the Zn metal surface, forming H2O-poor electrical double layer and regulating the nucleation and growth of Zn ions, and thus protecting the Zn anode from the detrimental side-reactions induced by water and dendrite growth. Benefiting from this versatility, the batteries exhibit high reversibility with 99.64 % coulombic efficiency and outstanding stability (over 600 h at 10 mA·cm−2/10 mAh·cm−2). Even cycled at harsh conditions of 20 mA·cm−2/20 mAh·cm−2, the remarkable stability of 100 h is obtained. The Zn//V2O5 full battery delivers high specific capacity of 249 mAh/g with capacity retention of 87.1 % after 5000 cycles.