[en] Highlights: • A SOFC stack integrated with catalytically enhanced porous media combustion. • The coating of 0.5 wt% Rh improved the reforming efficiency from 49% to 64.8%. • The maximum fuel utilization of FFC reached 32.6%. • Significant FFC electrical efficiency of 12.9% was obtained. -- Abstract: The flame fuel cell (FFC) is advantageous for its simple setup, quick start-up, and high fuel flexibility. However, one important drawback of the FFC is its relatively low electrical efficiency, which is mainly limited by the reforming efficiency of the burner and fuel utilization. In this study, to increase the reforming efficiency and fuel utilization, a catalytically enhanced porous media combustor was integrated with a micro-tubular solid oxide fuel cell stack. The second layer of the porous material was impregnated with 0.5 wt% Rh, improving the reforming efficiency from 49% to 64.8%. The fuel utilization was demonstrated to be 32.6% when the equivalence ratio was 1.6 and the inlet flow rate of combustion products to the anode of the stack was 200 mL min⁻¹. The effects of the equivalence ratio and anode gas flow rate on the electrochemical performance and efficiency were investigated. A power density of 72.9 mW cm⁻² and a total electrical efficiency of 12.9% were obtained at a voltage of 0.76 V and an equivalence ratio of 2.4.

[en] Highlights: • A flat-chip solid oxide fuel cell was fabricated and applied in flame fuel cell. • The flat-chip fuel cell endured a rapid temperature change rate of 5 °C/s. • It took less than 10 s for the start-up of flat-chip flame fuel cell. • 8 h discharging showed only 0.01 A/h degradation under harsh flame condition. -- Abstract: The flame fuel cell is a novel kind of fuel cell that directly combines a fuel-rich flame and solid oxide fuel cells together. Because of their simple setup, low cost, quick start-up and shut-down as well as no extra thermal management, flame fuel cells have great potential in micro-combined heat and power systems and portable applications. However, the conventional solid oxide fuel cell configurations including planar ones and tubular ones, may cause some problems when used in flame fuel cells such as thermal stress, secondary flame front, and difficulty for mass production. To solve these problems, a newly developed flat-chip solid oxide fuel cell is proposed to be used in the flame fuel cell in this study. Combining the merits of both planar and tubular solid oxide fuel cells, the flat-chip fuel cell is advantageous for its simple fabrication technology, good thermal shock resistance and feasibility to scale up. A flat-chip solid oxide fuel cell is fabricated and then integrated with a catalytically enhanced porous media combustor, demonstrating a novel flat-chip flame fuel cell system. The heating time for the flat-chip solid oxide fuel cell by the fuel-rich flame is less than 10 min from room temperature to 800 °C, with a temperature change rate of 5 °C/s in the first stage. The start-up time of the flat-chip flame fuel cell is less than 10 s. When the gas velocity is 6.0 cm/s and the equivalence ratio is 2.0, a peak power density of 179 mW/cm² is obtained for a single cell. Although there exists a remarkable temperature gradient, a small current degradation of 0.01 A/h is observed after a constant-voltage discharging at 0.5 V for 8 hrs. In addition, the flat-chip solid oxide fuel cell can be further scaled up in dimension, resulting in higher fuel utilization of flame fuel cell.