Zinc (II) chloride-based deep eutectic solvents for application as electrolytes: Preparation and characterization

Deep eutectic solvents (DESs) have gained interest due to their favorable electrochemical properties. This work introduced a new group of zinc (II) chloride based DESs and characterized their melting temperatures, viscosities, electrical conductivities, refractive indices, as well as electrical window over a wide range of temperatures. The ammonium-based deep eutectic solvents possessed lower melting temperatures, lower viscosities and higher electrical conductivities in comparison to phosphonium-based ones. The deep eutectic solvent made from choline chloride and zinc (II) chloride at a mole ratio of 1:1 possessed high conductivities, 574-4779 μS·cm^{- 1}, relatively low viscosities, 0.8278-0.2842 Pa·s, and wide electrochemical window, 3.74 V within the studied temperature range. The attained measurements were compared with other reported deep eutectic solvents in the literature.