Sodium nickel chloride (Na/NiCl₂) battery is one of the most promising candidates as a large scale electrochemical energy storage device. The battery comprises molten Na and NiCl₂ as negative and positive electrodes, respectively, in its charged state, separating them by a β”-Al₂O₃ solid electrolyte (BASE). In order to facilitate fast sodium ion transport in the cathode compartment, molten NaAlCl₄, as a secondary electrolyte (or catholyte), is infiltrated into the cathode materials powder. The battery typically operates at 250~300^oC so as to maximize the ionic flux in the NaAlCl₄ and through the solid electrolyte, and to minimize the dissolution of NiCl₂into the melt. However, this efficient battery is yet to be widely used in grid scale energy storage applications since it is still expensive and hard to dramatically reduce the cell price mainly due to its use of expensive sealing technologies.

The presentation introduces Korea-US collaborative efforts to develop a lower temperature operating sodium beta-alumina battery (LT-NBB) with a Na/NiCl₂ chemistry. Since the novel battery runs at below 200^oC, it can be fabricated at an ultra low manufacturing cost by introducing a new planar cell design with a greatly reduced number of cell components, and by eliminating expensive conventional sealing technologies. Enhanced degradation resistance of cathode materials is another important advantage of this technology. In this presentation, challenges and progress in building 5Wh class prototype LT-NBB cells using BASE with 70 mm in diameter will be discussed.