Stabilities and performance of single cubic phase dysprosium and zirconium co-doped bismuth oxide electrolytes for low temperature solid oxide fuel cells

Abstract

Low-temperature solid oxide fuel cells (LT-SOFCs), which can operate at 600 °C or lower, have recently emerged as a promising technology for widespread applications because of their low cost and high stabilities. Novel electrolyte materials with excellent ionic conductivities and stabilities are increasingly in demand for application in LT-SOFCs. Herein, a dysprosium and zirconium co-doped face-centered cubic phase-stabilized bismuth oxide (DZSB) electrolyte has been synthesized using the reverse co-precipitation method. Dysprosium and zirconium are selected to co-dope bismuth oxide because of their large radii and high polarizabilities, which can enhance conductivity stabilities. Dysprosium and zirconium can uniformly replace Bi sites and single-cubic phase DZSB powders of ∼150nm can be synthesized at 700 °C. High relative densities of sintered DZSB pellets (>95%) are obtained via calculations and scanning electron microscopy. D15Z5SB, which contains 15 mol% dysprosium and 5 mol% zirconium, presents the highest ionic conductivity of 0.037 S cm⁻¹ at 500 °C. The activation energy of the ionic conductivity of D2Z5SB shows a single value of 1.23 eV at high- and low-temperature regions. D20Z5SB and D25Z5SB show excellent stabilities for 450 h at 500 °C, with conductivities of 0.007 and 0.0026 S cm⁻¹, respectively.