The development of practical solid-state
sodium–metal batteries
calls for simple but efficient solutions to overcome poor anode||electrolyte
compatibility. Here, we for the first time, design an interphase comprised
of NaCl, Sn, and Na–Sn alloy formed in situ at room temperature to stabilize the Na||Na3Zr2Si2PO12 interface. Equipped with the dynamically
stable, low-impedance, and dendrite-free interface, the symmetric
cells demonstrate a 31-fold reduction in interfacial resistance, a
high critical current density to 0.8 mA cm–2, along
with a 1000-h cyclability at 25 °C. The corresponding Na||Na3V2(PO4)3 full cells showcase
a capacity retention rate of 93% after 1071 cycles at 0.5 C.