Interface Stability Control by an Electron-Blocking Interlayer for Dendrite-free and Long-Cycle Solid Sodium-Ion Batteries

Solid sodium-ion batteries (SSIBs) with high safety and high energy density have broad application prospects. Unfortunately, the poor contact and dendrite growth between sodium and the solid electrolyte severely hinder their development. Herein, an in-situ-forming electron-blocking interlayer (EBI) has been designed on the surface of Na3.2Hf1.9Ca0.1Si2PO12 (NHSP). The EBI could effectively improve the interface wetting and block the transmission of electrons, so as to ensure the long-term stability between sodium and the NHSP electrolyte. The batteries with the EBI@NHSP electrolyte could cycle stably for more than 700 h at 0.2 mA cm–2. Even with the increase of the current density to 2.3 mA cm–2, the batteries could still work normally. The full cell with the Na3V2(PO4)3 cathode also exhibited a good long-term cycling stability, which could cycle stably for more than 300 cycles at 0.5 C while maintaining a high Coulombic efficiency of 99.76%. This work provides a new feasible strategy to prevent sodium dendrite growth and promote the development of SSIBs.