2-methyl imidazole electrolyte additive enabling ultra-stable Zn anode

Abstract

Although aqueous zinc ion batteries are considered to be a promising next-generation energy storage battery, their commercialization is limited by the stability and safety issues of zinc anode. Herein, 2-methyl imidazole (Hmim) is introduced as electrolyte additive to in-situ construct a robust inorganic–organic zinc-rich (Zn4SO4(OH)6/Zn(Hmim)) solid electrolyte interface film for realizing high-stable dendrite-free Zn anode. On one hand, the zincophilic properties of Hmim and its chelation with Zn2+ result in more active sites for initial nucleation, leading to the uniform zinc deposition, and the change of coordination environment makes the diffusivity of ions decrease and the nucleation overpotential increase, which result in smaller grains in the initial zinc deposition stage. On the other hand, the formed inorganic–organic solid electrolyte interface film with good chemical and thermal stability can protect Zn anode well, and thus the side reactions and zinc dendrites can be effectively inhibited. Consequently, the Hmim-based electrolyte promotes dendrite-free Zn plating/striping with high Coulombic efficiency (97.32 %) and highly stability (cycling up to 2000 h). When applied in full cell, the Zn-V2O5 cell also demonstrates outstanding electrochemical performances. This work provides a simple and effective method for the implementation of high performance and high safety zinc-ion batteries.