Electrochemical characteristics and performance of anode-supported SOFCs fabricated using carbon microspheres as a pore-former

Abstract

This paper evaluates the influence of carbon microspheres (CMSs) as an electrode pore-former on the fabrication and electrochemical properties of the anode-supported solid oxide fuel cells (SOFCs). The anode supports are fabricated by dry-pressing of CMS and NiO/YSZ (nickel-oxide/yttria-stabilized zirconia) composite powder, and the YSZ electrolyte layer is prepared by the electrophoretic deposition technique. The ohmic and polarization resistances for NiO/YSZ–YSZ half cells at different testing temperatures (650–850 °C) are analyzed by electrochemical impedance spectroscopy (EIS). The polarization ASR (area specific resistance) for the fabricated half cells increases from 0.583 Ω cm2 to 3.047 Ω cm2 when the temperature decreases from 850 °C to 650 °C. The electrochemical performance of single cells is measured at different temperatures (700–850 °C) and the results indicate that the cells fabricated using CMS as the pore-former exhibit much higher electrochemical performance than those without using CMS. A maximum power density of 207.7 mW cm−2, 431.2 mW cm−2, and 571.6 mW cm−2 is recorded at 850 °C for the cells fabricated by adding 0 wt. %, 2.5 wt. % and 5 wt. % of CMS, respectively. The maximum fuel utilization efficiency is also found to increase from 26.5% for the cell prepared without CMS to 47.0% and 59.6% for the cells prepared with 2.5 wt. % and 5 wt. % of CMS, respectively. The increase in the electrochemical performance by adding CMS as pore-former to anode-supports is attributed to higher porosity and pore size of the electrode.