Porous NiO–YSZ and Ni–YSZ composites fabricated using NiO–YSZ composite nanopowders and WO3 additive

Abstract

NiO–YSZ composite nanopowders were synthesized through a hydrothermal process without an additional mixing of NiO and YSZ nanopowders. Porous Ni–yttria stabilized zirconia (YSZ) composites, Ni–YSZ composites, with high porosity (25.0–32.8%) were fabricated by reducing NiO-YSZ composites in (94% Ar + 6% H2) gas. The electrical conductivity (14,221 cm−1 at 30 °C) and bending strength (130 MPa) of Ni–YSZ composites were enhanced by the addition of WO3 (0.1 wt% WO3) to NiO–YSZ composite nanopowders. Furthermore, the Y2(WO4)3 with a negative coefficient of thermal expansion (CTE) reduced the CTE of Ni–YSZ composites. The CTE values of 0 and 0.6 wt% WO3–added Ni–YSZ composites were 13.8 × 10−6 and 12.4 × 10−6 °C−1, respectively. We demonstrate that the fabrication of NiO–YSZ composite nanopowders and the addition of WO3 to the NiO–YSZ composite nanopowders are highly effective methods for the fabrication of high-quality Ni–YSZ anode materials in solid oxide fuel cells.