Y₂Mo₃O₁₂–Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ cathode catalyst for proton-conducting solid oxide fuel cells

The mismatch of the coefficients of thermal expansion between cathode and electrolyte is one of the thorniest problems for high-performance proton-conducting solid oxide fuel cells (H–SOFCs). Here one strategy is applied by introducing the negative thermal expansion component, Y₂Mo₃O₁₂ (YMO), on Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) cathode to overcome this difficulty. As a result, not only the electrolyte-cathode connection but also the cell performance is improved. The maximum power density of the cell using a composite cathode reaches 1010.9 mW cm⁻² at 700 °C. The YMO softens the stress on the contact layer that keeps the cathode from delamination, which is confirmed by simulation studies and experiments. Furthermore, the A-site defect on BSCF created by the reaction between YMO and BSCF also plays a positive role in the oxygen reduction reaction (ORR) activity. This study provided a new way to study and improve the thermo-mechanical stability and cell performance of H–SOFCs.