Alkali Metal Reduction Potentials Measured in Chloroaluminate Ambient‐Temperature Molten Salts

Abstract
Alkali metal electrochemical reductions at a mercury film electrode (MFE) were studied in (MEIC = 1‐methyl‐3‐ethylimidazolium chloride) molten salts buffered to a neutral composition with . The MFE was formed by mercury deposition on a 127‐μm iridium disk electrode. At the Ir‐MFE, the reduction potentials for the Li, Na, K, Rb, and Cs amalgams were observed at −1.16, −1.26, −1.62, −1.67, and −1.75 V (vs. Al/Al(III)), respectively. By comparison of the amalgam reduction potentials in the melts to aqueous data, the formal reduction potentials for the elemental alkali metals in the buffered neutral melts are calculated to be −2.14, −2.15, −2.71, −2.77, and −2.87 V (vs.Al/Al(III)), for Li, Na, K, Rb, and Cs, respectively. The solvation energies for the alkali metals in the chloroaluminate molten salts are calculated to be approximately 4 to 15% lower than aqueous solvation energies.