Acetonitrile-Based Electrolytes for Rechargeable Zinc Batteries

Abstract

Herein, Zn plating–stripping onto metallic Zn using a couple of acetonitrile (AN)-based electrolytes (0.5 m Zn(TFSI)2/AN and 0.5 m Zn(CF3SO3)2/AN) is studied. Both electrolytes show a reversible Zn plating/stripping over 1000 cycles at different applied current densities varying from 1.25 to 10 mA cm−2. The overpotentials of Zn plating–stripping over 500 cycles at constant current of 1.25 and 10 mA cm−2 are ±0.05 and ±0.2 V, respectively. X-ray photoelectron spectroscopy analysis reveals that no decomposition product is formed on the Zn surface. The anodic stability of four different current collectors of aluminum foil (Al), carbon-coated aluminum foil (C/Al), TiN-coated titanium foil (TiN/Ti), and multiwalled carbon nanotube paper (MWCNT-paper) is tested in both electrolytes. As a general trend, the current collectors have a higher anodic stability in Zn(TFSI)2/AN compared with Zn(CF3SO3)2/AN. The Al foil displays the highest anodic stability of ≈2.25 V versus Zn2+/Zn in Zn(TFSI)2/AN electrolyte. The TiN/Ti shows a comparable anodic stability with that of Al foil, but its anodic current density is higher than Al. The promising reversibility of the Zn plating/stripping combined with the anodic stability of Al and TiN/Ti current collectors paves the way for establishing highly reversible Zn-ion batteries.