Bismuth tungstate/neodymium-doped ceria composite electrolyte for intermediate-temperature solid oxide fuel cell: Sintering aid and composite effect

Abstract

We demonstrate the utilization of bismuth tungstate (Bi2WO6, BW) as a sintering aid and reinforcement component into neodymium-doped ceria (Nd0.2Ce0.8O3-δ, NDC) to fabricate bismuth tungstate/neodymium-doped ceria composite electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFC). The presence of BW lowers the sintering temperature of NDC electrolyte to 1000 °C. Moreover, at 600 °C, the electrical conductivity of 5 mol.% BW-incorporated NDC (5BW-NDC) composite electrolyte is 7.12 times higher than the NDC. It is worth mentioning that the enhanced electrical conductivity of 5BW-NDC composite electrolyte does not include the contribution from electronic conductivity. Furthermore, NDC and 5BW-NDC exhibit excellent compatibility with La0.6Sr0.4Co0.8Fe0.2O3-δ cathode and NiO anode in terms of thermal expansion coefficient and chemical reactivity. The oxygen reduction reaction at 5BW-NDC composite electrolyte/cathode interface is significantly enhanced by ∼40% compared to NDC. Moreover, 5BW-NDC electrolyte-supported SOFC delivers a power density of 0.86 W cm−2 at 700 °C, which is 45.76% higher than the NDC-based SOFC. The output performance remains stable during high-temperature operation for 120 h, which indicates the stability and chemical compatibility of the as-synthesized composite electrolyte with other cell components. The results reveal that BW-NDC composite is a potential electrolyte material for stable and high-performance IT-SOFCs.