NASICON‐structured Na 3.1 Zr 1.95 Mg 0.05 Si 2 PO 12 solid electrolyte for solid‐state sodium batteries

Abstract Using stable inorganic solid electrolyte to replace organic liquid electrolyte could significantly reduce potential safety risks of rechargeable batteries. Na‐superionic conductor (NASICON)‐structured solid electrolyte is one of the most promising sodium solid electrolytes and can be employed in solid‐state sodium batteries. In this work, a NASICON‐structured solid electrolyte Na 3.1 Zr 1.95 Mg 0.05 Si 2 PO 12 was synthesized through a facile solid‐state reaction, yielding high sodium‐ionic conductivity of 1.33 × 10 −3 S·cm −1 at room temperature. The results indicate that Mg 2+ is a suitable and economical substitution ion to replace Zr 4+ , and this synthesis route can be scaled up for powder preparation with low cost. In addition to electrolyte material preparation, solid‐state batteries with Na 3.1 Zr 1.95 Mg 0.05 Si 2 PO 12 as electrolyte were assembled. A specific capacity of 57.9 mAh·g −1 is maintained after 100 cycles under a current density of 0.5C rate at room temperature. The favorable cycling performance of the solid‐state battery suggests that Na 3.1 Zr 1.95 Mg 0.05 Si 2 PO 12 is an ideal electrolyte candidate for solid‐state sodium batteries.