Nanoscale Al2O3 coating to stabilize selenium cathode for sodium-selenium batteries

Abstract

Na-Se batteries are promising energy storage systems for grid and transportation applications, due to the high volumetric energy density and relatively low cost. However, the development of Na-Se batteries has been hindered by the shuttle effect originating from polyselenide dissolution from the Se cathode. Herein, we reported the utilization of nanoscale Al2O3 surface coating by atomic layer deposition (ALD) to protect a microporous carbon/Se (MPC/Se) cathode and reduce polyselenide dissolution. Compared with the pristine MPC/Se, Al2O3-coated MPC/Se cathode exhibited improved discharge capacity, cycling stability, and rate capability in Na-Se batteries. Post-cycling analysis disclosed that Al2O3 coating on MPC/Se cathode effectively suppressed the polyselenide dissolution, facilitated the formation of thin and stable solid electrolyte interphase (SEI) layers, and reduced charge transfer resistance, thus improving the overall performance of Na-Se batteries. This work suggests the effectiveness of interface control by ALD in enabling high-performance Na-Se batteries and might shed light on the development of new-generation Li/Na/K-chalcogenide batteries.