Regulating the Interfacial Performance of All-Solid-State Sodium Batteries Using Lanthanum Substitution in a Na₃Zr₂Si₂PO₁₂ Solid Electrolyte

The main issues currently facing solid-state batteries are the low ionic conductivity of solid electrolytes and high interfacial resistance. By employing a doping strategy to introduce La 3+ into the Na 3 Zr 2 Si 2 PO 12 solid electrolyte increases the ionic conductivity to as high as 1.1 mS cm –1, promotes Na 3 La(PO 4 ) 2 interphase formation, and enhances interfacial charge transfer and cycling stability. The anode interfacial resistance of the Na 3.1 Zr 1.9 La 0.1 Si 2 PO 12 electrolyte decreased to 75 Ω cm 2 at room temperature, merely one-fourth smaller than that of Na 3 Zr 2 Si 2 PO 12 . Moreover, Na 3.1 Zr 1.9 La 0.1 Si 2 PO 12 achieves superior stable sodium plating/stripping cycling over 1800 h, and its performance exceeds that of most reported sodium solid electrolytes. A solid-state Na 3 V 2 (PO 4 ) 3 /Na 3.1 Zr 1.9 La 0.1 Si 2 PO 12 /sodium battery is assembled, demonstrating stable cycling performance with 84.5% capacity retention after 750 cycles. The enhancement of ionic conductivity in the solid electrolyte and the improvement of anode interfacial wettability have facilitated the advancement of solid-state sodium batteries.