Screening of Sintering Aids for Oxide Ceramics: A Case of NASICON Electrolyte

In this work, an efficient screening method to select appropriate sintering aids for a wide range of oxide material systems is developed. Consequently, Na2 B4 O7 , NaF, and CuO are selected as sintering aids for sodium super ionic conductor (NASICON)-type Na3 Zr2 Si2 PO12 ceramic to verify the feasibility of the as-proposed method. As evidenced by the results, the sinterability and densification of ceramic matrix are apparently improved. Specifically, Na3 Zr2 Si2 PO12 -7%Na2 B4 O7 , Na3 Zr2 Si2 PO12 -3%NaF, and Na3 Zr2 Si2 PO12 -3%CuO endow much higher room temperature ionic conductivity of 1.03 × 10-3 , 1.61 × 10-3 , and 1.63 × 10-3 S cm-1 , respectively, in comparison with the pristine (7.23 × 10-4 S cm-1 ). The underlying mechanism for the enhanced performance is also discussed. The symmetric sodium cells assembled with sintering aids modified Na3 Zr2 Si2 PO12 ceramic electrolyte exhibit ultra-stable metallic Na plating/stripping at room temperature. Moreover, solid-state sodium batteries paired with Na3 V1.5 Cr0.5 (PO4 )3 cathode active material and modified Na3 Zr2 Si2 PO12 ceramic electrolyte demonstrate superior cycling stability and excellent rate capability. Furthermore, an as-developed strategy can be universally extended to synthesize high-performance oxide ceramics.