Sodium-Metal Battery Based on Reversible Oxide Chemistry at the Cathode

Sodium-metal batteries are considered as a promising energy storage alternative for currently available lithium-based batteries owing to their high gravimetric energy density and more specifically the natural abundance and the low price of Na metal that can lead to an inexpensive and low weight battery technology. In this study, we employ a Na-metal cell design that works based on reversible phase/composition change of sodium oxides (superoxide and peroxide) using a highly active cathode catalyst and an ether-based ionic-liquid electrolyte. The process involves in-situ production of sodium oxides in the controlled oxygen environment at the cathode. Subsequently, the cathode composed of sodium oxide compositions is assembled into a Na-metal architecture to do performance study and analysis. Our results indicated that the designed Na-metal battery demonstrates stable performance over 50 cycles with an overpotential of less than 100 mV and a coulombic efficiency exceeding 99%. Various electrochemical and physicochemical characterization techniques, including Raman spectroscopy, X-Ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission Electron Microscopy (TEM), were employed to gain insight into cell chemistry and mixed ion-electron conduction mechanism. The findings underscore the significance of well-designed cell components in Na-O2 battery technologies, positioning them as a promising avenue in energy conversion and storage systems.