Tuning the growth of faceted Na3Zr2(SiO4)2PO4 NASICON-type solid electrolyte and its effect on microstructure-conductivity relationship

Abstract

NASICON-like Na3Zr2(SiO4)2PO4 (NZSP) ceramic solid electrolyte with high ionic conductivity, safety and durability becomes the main focus and attention as an alternative for traditional liquid electrolytes. NZSP containing NH4H2PO4 and Na3PO4⋅12H2O as the phosphate source have been extensively studied as a solid electrolyte, but a deep understanding of the relationship between crystal growth and ionic conductivity is still lacking. Herein, we synthesized NZSP via solid-state reaction using NaH2PO4 as the phosphate source. The impact of different sintering holding time on the crystal phase, microstructure, ionic conductivity and relaxation time of NZSP solid electrolytes were investigated. Microstructure studies revealed that the faceted NZSP sintered at 1100°C for 24 h has the lowest formation ZrO2, highest densification with the least pores. In addition, the sample achieved the highest room temperature ionic conductivity (4.11 ⋅ 10− 4 S cm-1) and the shortest relaxation time (0.4 µs), which is also are crucial factors for the development of rechargeable all-solid-state batteries (ASSBs).