BaO-modified finger-like nickel-based anode for enhanced performance and durability of direct carbon solid oxide fuel cells

Abstract

Direct carbon solid oxide fuel cells (DC-SOFCs) are hopeful high-temperature energy conversion devices with all-solid-state structure, high efficiency, and low emission. The anode catalytic activity is a direct limiting factor in the electrochemical performance of DC-SOFCs. Here, we successfully fabricated a finger-like Ni-based anode/electrolyte in one step, followed by infiltrating BaO within the anode, which significantly improved the anodic reaction and DC-SOFC performance. At 850 °C, the BaO/Ni-YSZ anode-supported DC-SOFC gave the optimal output of 505 and 825 mW cm−2 powering by activated carbon and hydrogen, respectively, which were significantly superior to those of the cell with traditional Ni-YSZ anode. Moreover, DC-SOFC with BaO/Ni-YSZ anode exhibited more stable operation for 20.9 h under 100 mA at 850 °C, giving a relatively high fuel utilization of 23.4 %. These excellent performances can be partially attributed to the smaller particle sizes and more grain boundaries of the BaO/Ni-YSZ anode due to the BaO infiltration, which effectively enhanced the ionic conductivity and mechanical strength of the anode. More importantly, density functional theory simulation revealed that the infiltrated BaO in the Ni-YSZ anode enhanced the adsorption ability of Ni sites for carbon monoxide and oxygen ions, which led to the increased differential charge densities and the reduction in the energy barrier of electrochemical oxidation reaction, thus effectively improving DC-SOFC performance and conversion efficiency.