The application of sodium anodes is essential for developing high-energy density, low-cost, and high-security solid-state sodium–metal batteries (SSSMBs) to replace commercial lithium ion batteries. However, poor interface contact, high resistance, and dendrite growth between the sodium anode and solid-state electrolyte (SSE) have hampered the application of SSSMBs. Herein, an ultrastable composite sodium anode with gradient ion-electron conductive phases was constructed through the in situ conversion and alloying reaction between SbF3 and sod...
