PNNL

Abstract

Na-beta alumina batteries (NBBs) are one of the most promising technologies for renewable energy storage and grid applications. Commercial NBBs are typically constructed in tubular designs, primarily because of their ease of sealing. However, planar designs are considered superior to tubular designs in terms of power output, cell packing, ease of assembly, and thermal management. In this paper, the performance of planar NBBs has been evaluated at an intermediate temperature. In particular, planar Na-NiCl2 cells with different cathode loadings and thicknesses have been studied at 190oC. The effects of the cathode thickness, charging current, and discharging power output on the cell capacity and resistance have been investigated. More than 60% of theoretical cell capacity could be retained with constant discharging power levels of 600, 525, and 300 mW for 1x, 2x, and 3x cathode loadings, respectively. The cell resistance with 1x and 2x cathode loadings was dominated by ohmic resistance with discharging currents up to 105 mA/cm2, while for 3x cathode loading, it was primarily dominated by ohmic resistance with currents less than 66.7 mA/cm2 and by polarization resistance above 66.7 mA/cm2.