Development of a high specific power sodium sulfur cell

The purpose of this R&D program is to explore the high-power capabilities of Na/S flat plate cells by testing standard cylindrical cells with active bases (only) at high rates under steady loads, and to utilize this data to support a proof of concept (POC) flat plate cell design. Typically, the test cells were discharged continuously to a specified depth of discharge (DOD) at a constant rate between 0.1 to 1.4 A/cm² in successive steps of 0.1 A/cm². The methods of determining the ohmic and polarization contributions are described. As part of the cell development activity, 113 mm thick beta" alumina membranes were tape cast and blanked to a 5 cm diameter, as sized by radial stress limitations. On the basis of test data and component engineering and evaluation, a 3.5 Ah (theoretical) POC cell design has emerged for high-power applications. In a logical extension of the POC cell, a conceptual design of a bipolar cell stack arrangement was predicted to achieve a power performance of 613 W/kg and 1.65 kW/L