Energy Storage in Electrochemical Cells with Molten Sb Electrodes

An energy-storage concept is proposed using molten Sb as the fuel in a reversible solid-oxide electrochemical cell (SOEC). Because both Sb and Sb 2 O 3 are liquids at typical SOEC operating temperatures, it is possible to flow Sb from an external tank and use it as the fuel under fuel-cell conditions and then electrolyze Sb 2 O 3 during recharging. This concept was tested using a button cell with a Sc-stabilized zirconia electrolyte at 973 K by measuring the impedances under fuel-cell and electrolyzer conditions for a range of stirred Sb-Sb 2 O 3 compositions. The Sb-Sb 2 O 3 electrode impedances were found to be on the order of 0.15 Ωcm 2 for both fuel-cell and electrolyzer conditions, for compositions up to 30% Sb and 70% Sb 2 O 3 . The open circuit voltages (OCV) were 0.75 V, independent of oxygen composition. Some features of using molten Sb as an energy-storage medium are discussed.