Co-Generation of Electricity and Chemicals via Solid Oxide Fuel Cells Using Li-Doped LSGM and LSF Composite Anodes

Abstract

In this work, co-generation of C2+ hydrocarbons and electricity in solid oxide fuel cells (SOFCs) was realized using methane as fuel. The SOFCs were prepared with Li-La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM)/Lr0.7Sr0.3FeO3 (LSF) as the composite anode and LSGM and (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ (LSCF)/Sm0.2Ce0.8O2−δ (SDC) as the electrolyte and cathode, respectively. Among the anode materials, Li-LSGM has higher C2+ product selectivity. It can be seen from the XPS data that the doping of Li introduces a strong alkaline active center Li+O–, changes the lattice and electronic structure, and increases the surface absorption of oxygen species, which is more conducive to the improvement of the selectivity of C2+ products. LSF has strong electron-conducting ability and high catalytic activity for methane. After mixing with Li-LSGM, XPS data show that more oxygen vacancies are generated, which is beneficial to the electrochemical reaction of the anode and effectively reduces carbon deposition. The maximum power density of the composite anode can reach 188.15 mW/cm–2 with H2 as the fuel at 850 °C, and a C2+ product selectivity of 57.48% is achieved with CH4 as the fuel at 800 °C and the current density is 40 mA/cm–2. In addition, the change of C2+ product selectivity with current density and temperature during cell operation was further investigated, providing enlightenment on how to adjust the output ratio of chemicals and electricity.