A facile method to stabilize sodium metal anodes towards high-performance sodium batteries

Abstract

Sodium metal is the ultimate anode for next generation high-energy-density sodium metal batteries due to its superior theoretical specific capacity, low redox potential, and natural abundance. However, sodium metal suffers from extreme and uncontrollable dendrite growth and gas evolution problems. These incidents result in a low coulombic efficiency and safety issues such as dangerous short circuits. Herein, an effective protective layer is fabricated on the Na metal anode via an extremely facile pretreatment method with 1,3-dioxolane. The protective layer exhibits fast interfacial transport and a lower resistance. Direct optical visualization shows that dendrite growth and gas evolution are suppressed due to the introduction of the protective layer. As a result, an outstanding cycling stability for 2800 h (1400 cycles) at 1 mA cm⁻² in a symmetric cell is obtained. Moreover, the full cell using the protected Na metal anode shows superior electrochemical performance in comparison to the untreated Na metal anode. Furthermore, large format protected Na metal anodes fabricated by spraying 1,3-dioxolane were demonstrated and successfully assembled in pouch cells, showing a stable specific capacity of around 95 mA h g⁻¹. Thus, our work presents a facile, efficient and scalable protection strategy to stabilize Na metal anodes towards high-energy-density sodium batteries.