Ultrafast sintering of Na3Zr2Si2PO12 solid electrolyte for long lifespan solid-state sodium ion batteries

The smart manufacturing of solid-state electrolytes (SSEs) plays an important role in the assembling, improvement and cost-reduction of high energy density solid-state batteries (SSBs). In this work, an ultrafast high-temperature sintering (UHS) method is employed to prepare the NASICON Na 3 Zr 2 Si 2 PO 12 ceramic SSEs in seconds. The prepared Na 3 Zr 2 Si 2 PO 12 (US-NZSPO) exhibits a high ionic conductivity of 2.62 × 10 −4  S cm −1 and low activation energy of 0.28 eV. The Na | US-NZSPO | Na symmetric cell delivers a cycling time over 270 h with a steady voltage overpotential at a current density of 0.5 mA cm −2 . Moreover, a Coulombic efficiency of 99.9 % and a capacity retention of 89 % are achieved at 0.2 C in Na 3 V 2 (PO 4 ) 3 (NVP) | US-NZSPO | Na solid cells after 800 cycles with the areal NVP loading of 4.5 mg cm −2 . These favorable electrochemical performances originate from the robust US-NZSPO pellet and well-constructed SSE-electrode interface, in which the electrochemically active interface demonstrates a strong self-stabilizing function to maintain the tight interfacial connections and the continuous Na + ion transport.