Performance of Nano-3YSZ toughened β’’-Alumina solid electrolyte prepared by EDTA-Zr(IV)/Y(III) complex as surface modifier

Due to its excellent ionic conductivity and electronic insulation, β/β″-alumina is widely used as a solid electrolyte in molten salt electrochemical cell and alkali metal thermoelectric convertor (AMTEC). In this article, nano-3mol% Yttrium partial stabilized zirconia (3YSZ) toughened β″-alumina solid electrolytes (BASEs) were fabricated by surface modification of β/β’’-alumina precursor particles with ethylenediaminetetraacetic acid (EDTA) - Zirconium (IV)/Yttrium (III) complex. The performance of BASEs with 0-10 wt% amount of nano-3YSZ addition (Zr-BASE) was systematically investigated on their phase composition, density, microstructure, bending strength, and conductivity. It was found that nano-3YSZ grains were intergranular and uniformly distributed in BASE matrix even at as low as 3 wt% amount of addition, which resulted in higher density, more homogeneous microstructure, higher Weibull modulus, higher characteristic strength and increased grain boundary resistance of Zr-BASE than those of BASE without 3YSZ addition. Zr-BASE with 5 wt% amount of nano-3YSZ addition demonstrated good conductivity (0.071 S•cm⁻¹ at 300 °C, 0.33 S cm⁻¹ at 600 °C) and higher characteristic strength (283 MPa). The obtained results indicated that surface modification by EDTA-Zr(IV)/Y(III) complex advantaged in the preparation of better performance BASEs with a small amount of nano-3YSZ addition.