Novel functionally graded acicular electrode for solid oxide cells fabricated by the freeze-tape-casting process

• Published in: Journal of power sources 2012-09, Vol.213, p.93-99
• Main Authors: Chen, Yu, Bunch, Jacob, Li, Tingshuai, Mao, Zhengping, Chen, Fanglin
• Format: Article
• Language: English
• Subjects: Acicular pore; Applied sciences; Density; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrode supported solid oxide cells; Electrodes; Electrolytic cells; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Freeze-tape-casting; Fuel cells; Functionally gradient materials; Oxidants; Oxides; Polarization resistance; Yttria stabilized zirconia; Zirconium dioxide
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2012.03.109

The performance of electrode supported solid oxide cells is often limited by gas transport in the thick electrode support. In this study, a novel functionally graded acicular hydrogen electrode microstructure has been fabricated by the freeze-tape-casting method. The effects of freeze-tape-casting processing parameters such as solid loading, freezing bed temperature and tape pulling rate on the morphology of the hydrogen electrode support have been investigated. The electrochemical performance of the cells having the novel functionally graded acicular hydrogen electrode has been significantly improved. In the fuel cell mode, a high power output of 1.28 W cm−2 and a low polarization resistance of 0.166 Ω cm2 have been achieved at 800 °C with H2 as fuel and ambient air as oxidant using nickel–yttria-stabilized zirconia (YSZ) as the hydrogen electrode, YSZ as the electrolyte, and (La0.75Sr0.25)0.95MnO3–YSZ as the oxygen electrode. In the electrolysis mode, a high current density of 2.3 A cm−2 with 30 vol% absolute humidity in the hydrogen electrode at 800 °C has been achieved with an applied cell voltage of 1.6 V. It has been revealed that the novel acicular hydrogen electrode decreases the gas diffusion resistance, thus enhancing the cell performance. ► Effects of freeze-tape-casting parameters on substrate morphology have been investigated. ► Fuel cells show output power of 1.28 W cm−2 and cell polarization resistance of 0.166 Ω cm2 at 800 °C. ► Electrolysis cells current density reach 2.3 A cm−2 at 800 °C with 30 vol% absolute humidity at 1.6 V.