Enhanced Sulfur Tolerance of Nickel-Based Anodes for Oxygen-Ion Conducting Solid Oxide Fuel Cells by Incorporating a Secondary Water Storing Phase

• Published in: Environmental science & technology 2014-10, Vol.48 (20), p.12427-12434
• Main Authors: Wang, Feng, Wang, Wei, Qu, Jifa, Zhong, Yijun, Tade, Mose O, Shao, Zongping
• Format: Article
• Language: English
• Subjects: Applied sciences; Electric Power Supplies; Electrodes; Electrolytes; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Hydrogen - chemistry; Hydrogen Sulfide - chemistry; Ions; Metals - chemistry; Nickel; Oxides - chemistry; Oxygen; Oxygen - chemistry; Solid oxide fuel cells; Sulfur; Sulfur - chemistry; Water; Water - chemistry
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es503603w

In this work, a Ni+BaZr0.4Ce0.4Y0.2O3‑δ (Ni+BZCY) anode with high water storage capability is used to increase the sulfur tolerance of nickel electrocatalysts for solid oxide fuel cells (SOFCs) with an oxygen-ion conducting Sm0.2Ce0.8O1.9 (SDC) electrolyte. Attractive power outputs are still obtained for the cell with a Ni+BZCY anode that operates on hydrogen fuels containing 100–1000 ppm of H2S, while for a similar cell with a Ni+SDC anode, it displays a much reduced performance by introducing only 100 ppm of H2S into hydrogen. Operating on a hydrogen fuel containing 100 ppm of H2S at 600 °C and a fixed current density of 200 mA cm–2, a stable power output of 148 mW cm–2 is well maintained for a cell with a Ni+BZCY anode within a test period of 700 min, while it was decreased from an initial value of 137 mW cm–2 to only 81 mW cm–2 for a similar cell with a Ni+SDC anode after a test period of only 150 min. After the stability test, a loss of the Ni percolating network and reaction between nickel and sulfur appeared over the Ni+SDC anode, but it is not observed for the Ni+BZCY anode. This result highly promises the use of water-storing BZCY as an anode component to improve sulfur tolerance for SOFCs with an oxygen-ion conducting SDC electrolyte.