No abstract

Solid oxide fuel cells (SOFCs), which directly convert chemical energy into electricity, have several advantages, such as fuel flexibility and low emissions. Unfortunately, the performance and stability of SOFCs with state-of-the-art Ni-based anodes are sensitive to impurities, such as sulfur, which is a common component of practical fuels, including natural gas and renewable biogas. The development of sulfur-tolerant anode materials is important for successfully operating SOFCs with sulfur-containing practical fuels. In this study, a core-shell architecture was fabricated from solution infiltration and was evaluated as a sulfur-tolerant anode for SOFCs. For the first time, we used a lithium conductive material, Li 0.33 La 0.56 TiO 3 (LLTO, perovskite oxide), as the shell for anodic reactions. The resulting cell delivered higher electrochemical activities than similar cells, with widely used sulfur-tolerant perovskite anodes. In addition, the cell with the core-shell structured anode demonstrated favorable stability over 70 hours' operation when using 1000 ppm H 2 S-H 2 fuel at 800 C. In contrast, the cell with an anode composed of nanoparticles failed after only 5.5 hours under the same operation conditions. This study offers a new strategy for developing highly sulfur tolerant and efficient anodes for SOFCs.

Solid oxide fuel cells (SOFCs) are the most widely used fuel cells due to their excellent fuel flexibility, high efficiency and low emissions. Although the liquid fuels are easier to handle and transport than hydrogen, their direct use in SOFC leads to serious performance deterioration because of the coke formation on the traditional Ni‐based cermet anodes. In this review, the advances in the development of coking resistant anodes and the new liquid fuels such as oxygenated hydrocarbons to solve the problem of coke formation with Ni‐based anodes are summarized. It is concluded that Ni‐based cermets are still the most promising anode materials and some targeted modifications are needed to improve the coking resistance. Several strategies to improve the coking resistance of Ni‐based anodes are highlighted. The aim of this review is to provide some helpful guidance and potential directions for the future design of anodes for SOFCs utilizing liquid oxygenated hydrocarbon fuels directly.

In this work, a Ni+BaZr(0.4)Ce(0.4)Y(0.2)O(3-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 Sm(0.2)Ce(0.8)O(1.9) (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.