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 La³⁺ into the Na₃Zr₂Si₂PO₁₂ solid electrolyte increases the ionic conductivity to as high as 1.1 mS cm^-1, promotes Na₃La(PO₄)₂ interphase formation, and enhances interfacial charge transfer and cycling stability. The anode interfacial resistance of the Na_3.1Zr_1.9La_0.1Si₂PO₁₂ electrolyte decreased to 75 Ω cm² at room temperature, merely one-fourth smaller than that of Na₃Zr₂Si₂PO₁₂. Moreover, Na_3.1Zr_1.9La_0.1Si₂PO₁₂ achieves superior stable sodium plating/stripping cycling over 1800 h, and its performance exceeds that of most reported sodium solid electrolytes. A solid-state Na₃V₂(PO₄)₃/Na_3.1Zr_1.9La_0.1Si₂PO₁₂/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.