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

Abstract

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.

Effect of Au and/or Mo Doping on the Development of Carbon and Sulfur Tolerant Anodes for SOFCs—A Short Review

“…In addition to the modification of surface adsorption properties of Ni, significant sulfur tolerance resistance can be obtained by modifying the ionic oxide support e.g., CeO 2 or the use of other mixed ionic/electronic perovskite materials like BaZr 0.1 Ce0.7Y 0.2−x Yb x O 3-δ (BZCYYb) or BaZr 0.4 Ce 0.4 Y 0.2O3−δ (BZCY), which can be oxygen ion or proton conductors (Wang et al, 2014;Chen et al, 2016). As for the case of carbon tolerance, CeO 2 supporting catalytic systems are characterized by the fast transition between Ce 4+ to Ce 3+ that provides highly mobile O species, which can oxidize adsorbed S species either on Ni or on CeO 2 .…”

Rational Design of a Water‐Storable Hierarchical Architecture Decorated with Amorphous Barium Oxide and Nickel Nanoparticles as a Solid Oxide Fuel Cell Anode with Excellent Sulfur Tolerance

“…Another important strategy for improving the coking/sulfur tolerance of Ni‐based anodes is to increase the gasification rate of deposited carbon/sulfur on the anode 21, 22, 23. In the oxygen‐ion‐conducting SOFCs, water is produced at the anode under current polarization, which can be used to remove the deposited carbon/sulfur on the anode.…”

“…In a pioneering work, Liu and co‐workers reported that BaO nanoparticles deposited on Ni surface can adsorb water, facilitating the rapid removal of the deposited carbon/sulfur on the anode 21. More recently, Shao and co‐workers demonstrated that using a water‐storable proton conductor in a Ni‐based anode resulted in excellent coking/sulfur resistance 22, 23. However, the operational stability of this anode was unsatisfactory due to the large Ni particle size and poor contact between Ni and the water‐storable phase 23…”

“…These results demonstrated the superior sulfur tolerance of the reduced BZCYN‐infiltrated SDC anode, which was further confirmed by the differences in the electrode polarization resistances (Figure S14, Supporting Information). As shown in Figure S14 in the Supporting Information, it was found that there were some differences in the ohmic resistances, which could be attributed to the reconstruction, diffusion, and loss of the Ni active sites in the Ni‐infiltrated SDC and BZCY‐infiltrated Ni+SDC anodes 23, 25. Due to the strong water‐storage capability of amorphous BaO and BZCY proton conductor in the reduced BZCYN‐infiltrated SDC anode, the deposited sulfur on the anode surface can be rapidly eliminated, which can prevent the formation of nickel sulfides (Ni 2 S 3 ) on the Ni surface.…”

A high performance ceria-based solid oxide fuel cell operating on underground coal gasification gas

“…Nevertheless, the study of SOFC fed with underground coal gasification (UCG) gas, a widely used hydrocarbon in China, Australia and India, is rarely reported [22,23]. And SOFC can convert chemical energy in the fuel directly to electricity with fuel flexibility, high efficiency, and low emissions of greenhouse gas such as CO 2 and environmental pollutants like NO x [25][26][27]. And SOFC can convert chemical energy in the fuel directly to electricity with fuel flexibility, high efficiency, and low emissions of greenhouse gas such as CO 2 and environmental pollutants like NO x [25][26][27].…”