Na3Zr2Si2PO12 solid electrolyte with Bi2O3 as sintering aid for solid-state sodium batteries.

Improving the density of Na₃Zr₂Si₂PO₁₂ (NZSP) solid electrolyte is crucial for its application in solid-state sodium batteries. Here, bismuth oxide with low melting point has been evaluated as a sintering aid for NZSP solid electrolytes. Research has found that NZSP doped with 5 mass% Bi₂O₃ increases grain boundary mobility by 3.1 times and has an ionic conductivity of 4.78 × 10⁻³ S cm⁻¹, with a minimum activation energy of 0.30 eV, approximately 5 times that of undoped Bi₂O₃. This is because the electrolyte density increased from 77.3 to 93.7%. Compared with the region III process of NZSP without Bi₂O₃, Bi₂O₃ promotes the densification process of Bi₂O₃ dopant coarsening in region III. The constant current cycle of Na | NZSP-5 mass% Bi₂O₃ | Na symmetric battery indicates that no short circuit will occur within 1200 h. The discharge capacity of solid-state batteries at 0.2 C is 98.5 mAh g⁻¹. This indicates that NZSP doped with 5% Bi₂O₃ is a good electrolyte choice for sodium-ion batteries. [ABSTRACT FROM AUTHOR]