Synthesis of Na-β-Al_2O_3 Nanopowders by PVP Sol-Gel Process

As the key material of the β-Al2O3electrolyte of sodium sulfur battery(SSB), the properties of Na-β-Al2O3 powders play an important role in the performance of SSB. In this study, nanosized Na-β-Al2O3powders were prepared by Sol-Gel process with polyvinyl pyrrolidone(PVP) as the chelating agent. The phase formation temperature of the Na-β-Al2O3 by the PVP-based process was reduced to 900 ℃, which was much lower than those of conventional SSR and most chemical synthesis methods. The new method can effectively inhibit the performance decline of the Na-β-Al2O3 ceramics induced by the volatilization of Na2O at high temperature in the conventional method. The powders were characterized by XRD, SEM and TEM techniques. It was demonstrated that the phase was pure and the particles were well dispersed with diameter of 60-70 nm, which were helpful to the good performance of Na-β-Al2O3 ceramics. In addition, the conductivities of the Na-β-Al2O3 ceramics sintered by the as-prepared powders were measured by AC impedance spectroscope and the evaluation of the spectra was carried out with increasing temperature from room temperature to 350 ℃.The electrical conductivity of the ceramics at 350 ℃ reached 0.22 S/cm.