Construction of low dielectric aqueous electrolyte with ethanol for highly stable Zn anode

Zinc (Zn) metal-based aqueous batteries are attracting tremendous attention facing grid-energy storage. However, the practical application has been severely impeded due to the challenges of Zn anode including the dendrites growth, side reactions and passivation layer accumulation. Here, an accessible solvent (ethanol, ETH) with low dielectric constant is utilized as an electrolyte additive to modulate the coordination environment of Zn2+ and the surface of Zn anode. The new assembled solvated ions reduce the inherent electrostatic interactions within the overall electrolyte, resulting in the efficient migration of Zn2+. In addition, the preferential adsorption of ETH on the Zn surface leads to the formation of an improved electric double layer (EDL), which effectively restricts water molecule access and regulates unique transfer channels of Zn2+. As a result, dense deposit with orientation plating is achieved. Zn||MnO2 full cells disclose an impressive capacity retention of 84.47% even after undergoing 2000 cycles at a high current density of 1 A g-1. This work provides a new insight into the effect of low dielectric constant additives on Zn2+ deposit for advanced aqueous zinc-ion batteries (AZIBs) development.