Completely sealed direct carbon solid oxide fuel cell with in situ steam-carbon gasification reaction

Abstract

Direct carbon solid oxide fuel cells (DC-SOFCs) offer the potential for clean and efficient conversion of chemical energy in carbon fuels into electricity. However, the reverse Boudouard gasification of carbon requires a high operating temperature (≥800 °C), which hinders the development of DC-SOFCs. We present a completely sealed DC-SOFC with in situ steam-carbon gasification. The cells have a symmetrical cell structure (Ag–Ce0.8Gd0.2O1.9/La0.9Sr0.1Ga0.8Mg0.2O3−δ/Ag–Ce0.8Gd0.2O1.9) and are loaded with K-loaded activated carbon fuel. Ca(OH)2 and Li4SiO4 are loaded into the anode chamber as the steam feedstock and CO2 sorbent, respectively. Completely sealed DC-SOFCs with Ca(OH)2–C of 0 %, 5 %, 10 %, 15 %, and 20 % have been tested at 700 °C. Compared with a cell with a conventional structure and a completely sealed cell without Ca(OH)2 loading, the electrochemical performances of all the completely sealed cells with Ca(OH)2 loading are significantly enhanced. The cell with Ca(OH)2 to C of 15 % obtained the highest maximum power density of 75 mW cm−2, which is approximately two-fold that of the conventional DC-SOFC. The mechanism for improving the performance of the cell is the introduction of steam. This study offers a new method to develop high-performance DC-SOFCs and reduce their operating temperatures.