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

Abstract In this work, an efficient screening method to select appropriate sintering aids for a wide range of oxide material systems is developed. Consequently, Na 2 B 4 O 7 , NaF, and CuO are selected as sintering aids for sodium super ionic conductor (NASICON)‐type Na 3 Zr 2 Si 2 PO 12 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, Na 3 Zr 2 Si 2 PO 12 ‐7%Na 2 B 4 O 7 , Na 3 Zr 2 Si 2 PO 12 ‐3%NaF, and Na 3 Zr 2 Si 2 PO 12 ‐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 Na 3 Zr 2 Si 2 PO 12 ceramic electrolyte exhibit ultra‐stable metallic Na plating/stripping at room temperature. Moreover, solid‐state sodium batteries paired with Na 3 V 1.5 Cr 0.5 (PO 4 ) 3 cathode active material and modified Na 3 Zr 2 Si 2 PO 12 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.