Phase Diagram and Conductivity of Zn(TFSI)2–H2O Electrolytes

A binary phase diagram of zinc bis(trifluoromethylsulfonyl)imide and water, Zn(TFSI)2–H2O, was mapped out from 0 to 0.375 mole fraction of salt, revealing the existence of di-, tetra-, hexa-, and octahydrates of Zn(TFSI)2. Samples of this solution in molalities from 0.060 to 4.2 were also measured for their electrolytic conductivity in the temperature range of (−40, 80) °C. The conductivity data were further fitted with a Vogel–Fulcher–Tammann-based function and compared with those of LiTFSI–H2O obtained previously, showing Zn(TFSI)2–H2O to be almost as conductive as LiTFSI–H2O despite the divalence of the cation.