Experimental and numerical study of micro-tubular direct carbon solid oxide fuel cell fueled by the oilseed rape straw-derived biochar

Direct carbon solid oxide fuel cells (DC-SOFCs) can directly utilize solid carbon to generate electricity. However, the fuel cells' carbon fuel sources and configuration may significantly affect their electrochemical performance. In this work, we systematically investigate the electrochemical performance of the micro-tubular DC-SOFC (MTDC-SOFC) using the oilseed rape straw (ORS)-derived biochar by experimental and simulation numerical studies. For the first time, the ORS biochar is introduced in DC-SOFCs to improve electrochemical performance. As expected, the single cell delivers the best output of 222 mW cm-2 at 850 degrees C, which is comparable to that of hydrogen-fueled SOFC. Besides, the MT-DC-SOFC exhibits a long operating lifetime of 11.9 h under a 100 mA constant current with the fuel utilization of 23.8% at 850 degrees C, verifying that the ORS biochar is an excellent carbon fuel for DC-SOFCs. Moreover, multi-physical field modeling is applied to evaluate the mechanism of the MT-DC-SOFC. The simulation results verify the experimental findings that the cell performance is significantly affected by the electrolyte with finger-like pores, carbon fuel location and area, and electrode thickness. This work presents a novel green strategy for developing high-performance MT-DC-SOFCs that can efficiently utilize the ORS biochar and other biomass.