Abstract:

All-solid-state sodium batteries are highly promising for large-scale energy storage due to their potential cost-effectiveness and safety. However, their practical application is hindered by the high interfacial impedance between solid electrolytes and sodium metal anode, as well as risks of sodium dendrite growth. In this work, an In₂S₃ interfacial layer is introduced on Na_3.4Zr_1.9Zn_0.1Si_2.2P_0.8O₁₂ (NZZSPO) solid electrolyte via magnetron sputtering, which reacts with sodium metal anode to in-situ form a Na-In alloy/Na₂S interlayer at NZZSPO/Na interface. The Na-In alloy/Na₂S interlayer enhances the wettability of the solid electrolyte/anode interface and reduces interfacial impedance, effectively improving the ability of NZZSPO@In₂S₃ solid electrolyte to suppress sodium dendrite formation. The results show that the critical current density of the symmetric battery based on NZZSPO@In₂S₃ solid electrolyte enhances significantly, increasing from 2.6 mA cm^-2 to 8.2 mA cm^-2 at 60℃ and from 1.6 mA cm^-2 to 2.2 mA cm^-2 at room-temperature. Meanwhile, Na|In₂S₃@NZZSPO@In₂S₃|Na symmetric battery exhibits superior cycling stability for 2000 hours at 60℃ and 5 mA cm^-2; even at room temperature, the battery can also operate stably at 1.5 mA cm^-2 for 1500 hours. Additionally, Na₃V₂(PO₄)₃|NZZSPO@In₂S₃|Na all-solid-state battery delivers an initial discharge capacity of 108.6 mAh g^-1 at 0.1C with a Coulombic efficiency of 95.4% and capacity retention of 94.8% after 100 cycles; when the current density increases to 1C, the battery still demonstrates a capacity retention of 88.8% after 1000 cycles. This work provides an in-situ approach for constructing a Na-In/Na₂S interlayer at the NZZSPO/Na interface, significantly enhancing the ability of solid electrolyte to suppress sodium dendrite growth and offering a promising strategy for developing high-performance all-solid-state sodium batteries.

Key words: all-solid-state sodium battery, oxide solid electrolyte, In₂S₃ interface layer, sodium metal anode