Y2Mo3O12–Ba0.5Sr0.5Co0.8Fe0.2O3-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, Y 2 Mo 3 O 12 (YMO), on Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 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. [Display omitted] • A negative expansion component Y 2 Mo 3 O 12 was used to balance the thermal expansion. • It is the first work using multi-scale simulations coupled with experiments for H–SOFCs. • The high thermal mismatch of Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ is mitigated. • A high fuel cell performance is obtained. [ABSTRACT FROM AUTHOR]