Highly conducting Sc and Y co-doped ZrO2 thin film solid electrolyte on a porous Ni/YSZ electrode prepared via simple drop-coating method

Abstract

Dense and crack-free thin film solid electrolyte of scandium and yttrium co-doped zirconia (Sc0.08Y0.08Zr0.84O1.92) or 4S4YSZ has been successfully deposited on a NiO-YSZ porous electrode substrate via simple drop-coating deposition method. The 4S4YSZ precursor powder was synthesized using sol-gel method and the NiO-YSZ substrate, with 1:1 wt% composition, was prepared via modified glycine-nitrate combustion method. The NiO-YSZ substrates were pre-sintered at different temperatures, 1000 °C and 1300 °C, to investigate the effect on the thin film deposition and its microstructure. XRD results showed that both 4S4YSZ and NiO-YSZ exhibited a cubic crystal structure with no observable impurity peaks. SEM-EDS revealed a dense morphology of 4S4YSZ thin film with thickness of about 7μm after sintering while maintaining a desirable porous NiO-YSZ microstructure of the electrode substrate for the 1000 °C pre-sintered substrate as compared to a still porous solid electrolyte for the higher substrate pre-sintering temperature at 1300 °C. And from the conductivity measurements using EIS, the 4S4YSZ thin film revealed a notable high total conductivity of about 1.2x10-1 Scm-1 at 700 °C with 0.73 eV activation energy. Reduction of NiO/YSZ to Ni/YSZ further increases the porosity of the electrode substrate while maintaining a dense solid electrolyte thin film.