Cathodic limiting potential, room-temperature

Separate the copper and antimony by dissolving the deposit in a mixture of 5 mL concentrated nitric acid, 5 mL 40 per cent hydrofluoric acid (CARE), and 10 mL water boil off the nitrogen oxides, dilute to 150 mL, and add dropwise a solution of potassium dichromate until the liquid is distinctly yellow. Deposit the copper by electrolysing the solution at room temperature and limiting the cathode vs S.C.E. potential to —0.36 volt. Evaluate the weight of antimony by difference. 

Matsumoto, H., H. Kageyama, and Y. Miyazaki. 2003. Effect of ionic additives on the limiting cathodic potential of EMI-based room temperature ionic liquids. Electrochemistry 71 1058-1060. 

Howlett, P. C. MacFarlane, D. R. HoUenkamp, A. R, High lithium metal cycling efficiency in a room-temperature ionic liquid, Electochem. Solid-State Lett., 2004, 7, A97-A101. Matsumoto, H. Kageyama, H. Miyazaki, Y., Effect of ionic additives on the limiting cathodic potential of EMI-based room temperature ionic liquids. Electrochemistry, 2005,71, 1058-1060. 

A three-electrode design using both a lithium reference and counter-electrode was used for cyclic voltammetry experiments. Electrolyte volume was 12.5 ml. Lower and upper voltage scan limits were from 2.0 to 4.0 volts relative to lithium with initial scan directions being cathodic of respective open circuit potentials. All data were obtained at room temperature and 100 mV/sec scan rates and referenced to a small lithium strip also immersed in the electrolyte. The lithium counter and reference electrodes remained shiny in all electrolytes studied and the potential of the SO reduction peak at 2.9 volts was essentially unchanged in all the solutions studied. This implies that at least over a one day time scale, no gross lithium corrosion was taking place. 

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