Reducing Interfacial Resistance by Na-SiO₂ Composite Anode for NASICON-Based Solid-State Sodium Battery

Abstract

Room-temperature solid-state sodium batteries (SSBs) are viewed as one of the most promising candidates for next-generation energy storage devices because of their cost-effectiveness, safety performance, and high energy density. Na+ ion superionic conductor (NASICON) type solid electrolyte (SE) shows great perspective due to its high ionic conductivity at room temperature. However, the high interfacial resistance between Na metal anode and NASICON SE is still thwarting the stable operation of SSBs. In this work, we successfully reduce the Na|NASICON interfacial resistance from 1658 to 101 Ω·cm2 by lowering surface tension of Na metal via compositing Na metal with amorphous SiO2. Enabled by the enhanced interface contact, the solid-state Na-SiO2|NASICON|Na-SiO2 symmetric cell can endure current density up to 500 μA/cm2 and stably cycle for more than 135 h, while Na|NASICON|Na symmetric cell shorts in less than 10 h under 100 μA/cm2. This Letter provides an effective route to form close contact between Na metal anode and NASICON SE and fuels studies concerning Na|NASICON interface in the future.