Physicochemical Properties of EMPyrCl-ZnCl2 Melts and Electrodeposition of Molybdenum from the Equimolar Melt at 150°C

A new molten salt system, N-ethyl-N-methylpyrrolidinium chloride (EMPyrCl)-ZnCl2, was investigated for the electrodeposition of molybdenum at intermediate temperature. A phase diagram was constructed for the EMPyrCl-ZnCl2 system, which shows the lowest melting point of 45°C at an equimolar composition. A thermal gravimetry indicated that thermal decomposition starts from 230°C for the equimolar melt. The viscosity and conductivity of the equimolar melt were 75 cP and 22 mS cm−1, respectively, at 150°C. The cathode limit of the equimolar melt was confirmed to be the deposition of metallic zinc by XRD analysis. A smooth metallic molybdenum film was electrodeposited on a nickel substrate by potentiostatic electrolysis at 0.01 V vs. Zn(II)/Zn in an equimolar melt containing MoCl5 (0.9 mol%) and KF (3.0 mol%) at 150°C.