Enhanced ionic conductivity of Ce-doped Na3Zr2Si2PO12 electrolyte for achieving superior performance of solid-state sodium batteries

Abstract

Solid-state sodium batteries (SSSBs) are gaining significant attention for their potential in electrochemical energy storage. However, the development of SSSBs is hindered by the low ionic conductivity of sodium-ion solid electrolytes (SSEs). Herein, Ce with a relatively large ionic radius is employed to replace Zr in Na3Zr2Si2PO12 (NZSP), aiming to increase the ionic conductivity of the SSEs. Through structural analysis and theoretical calculations, it is inferred that Ce doping is favorable for stabilizing phases with higher ionic conductivity, increasing the Na+ concentration via the substitution of Zr4+ with Ce3+, and facilitating the generation of a densified microscopic morphology. The Ce-doped NZSP achieves a high room-temperature conductivity of 2.08 mS·cm−1 and good interfacial compatibility with Na metal. Furthermore, the assembled Na3V2(PO4)3 cell based on Ce-doped NZSP maintains a capacity of 111.18 mAh·g−1 at 0.5 C after 200 cycles, with a high retention of 98.06%.

Keywords

• solid electrolyte
• na3zr2si2po12
• ce doping
• ionic conductivity
• solid-state battery