In Situ Construction of a Liquid Film Interface with Fast Ion Transport for Solid Sodium-Ion Batteries

Solid sodium-ion batteries (SSIBs) are considered as one of the promising energy storage systems because of their high safety and high energy density. However, the sodium metal anode presents poor wettability with a solid electrolyte, resulting in high interface impedance and dendrite growth, which severely limits their application in practice. Herein, a novel liquid film (Na-BP) interface is constructed between sodium and solid electrolyte (Na₃Hf₂Si₂PO₁₂) with an excellent kinetic mass transfer ability and good fluidity, which could guarantee a close contact and fast charge transfer at interface. The symmetric cells with the designed interface show a high-rate and long-cycle performance and could cycle stably more than 1000 and 700 h at 0.2 and 0.5 mA cm^-2, respectively. The critical current density of the cells can reach 3.6 mA cm^-2 at room temperature, which is the highest value in similar works.