Low Temperature Operation of the Cell Na/β'-Alumina/S(IV) in AlCl{sub}3-NaCl Melt

摘要

The cell Na/β"-alumina/S(IV) in AlCl{sub}3-NaCl melt had been operated almost exclusively in the temperature range 180° to 250°C. Lower temperature operation was explored using the acidic region of the AlCl{sub}3-NaCl phase equilibrium, which has a eutectic at 108°C, and the first step in the S(IV) discharge process (OCV>4.2V). When the commonly used low surface area current collector was used in the cathode, cell operation below 150°C led to only partial utilization of cell capacity. However, using a cathode constructed with a high surface area current collector (RVC) and operated exclusively in acidic melts, the cell was cycled down to 120°C. It was operated with essentially full capacity and produced ≈100% coulombic efficiency. Energy efficiency at 120° was 87%. Cell operation at and below 115°C led to incomplete and irreproducible discharges,. Low temperature operation of this cell can minimize or eliminate corrosion of cathode seal components and extend cell life-time. Because of these favorable properties this cell can find applications in energy storage as well as in downhole oilfield tools.