A rational design of FeNi alloy nanoparticles and carbonate-decorated perovskite as a highly active and coke-resistant anode for solid oxide fuel cells

Solid oxide fuel cells (SOFCs) are a kind of clean and efficient device to convert chemical energy in fuels into electricity. However, since anodes with high catalytic activity and carbon tolerance are still underdeveloped, the consequent serious performance degradation of the cells under operational conditions significantly confines their commercial applications. Here we propose a new strategy to remove carbon deposition by in-situ formation of alkali metal carbonate on the anode surface. A multi-phase composite anode, which is composed of an orthorhombic single perovskite main phase, a Ruddlesden-Popper (RP) layered perovskite second phase, and an in-situ exsolved FeNi alloy minor phase, is developed by one-step reduction of La_0.65Li_0.05Sr_0.3Fe_0.8Ni_0.2O_3-δ (LLSFN_0.05) at a high temperature. The deficiencies of the RP phase and A-site caused by Li dopant would increase oxygen bulk diffusion, and FeNi nanoparticles would boost the catalytic activity. Moreover, when dealing with carbon fuel, lithium carbonate can be synthesized on the anode surface, serving as a good oxygen ion conductor and an efficient catalyst for coke removal by gasification. A single cell with our reduced LLSFN_0.05 anode exhibited maximum power densities of 596, 467, and 424 mW cm⁻² at 750 ℃ with H₂, CO, and wet C₂H₆ as the fuel, respectively. In addition, the cells could have a long-term stable operation for over 80 h using CO as the fuel at 200 mA cm⁻². This study provides a new material design strategy to develop a highly active and coke-resistant anode.