Phase-inversion combined tape casting technology was applied to fabricate P-SOFCs, which demonstrated great performance for CH3OH containing fuel.

Driven by the demand to minimize fluctuation in common renewable energies, reversible solid oxide cells (RSOCs) have drawn increasing attention for they can operate either as fuel cells to produce electricity or as electrolysis cells to store electricity. Unfortunately, development of proton-conducting RSOCs (P-RSOCs) faces a major challenge of poor reliability because of the high content of steam involved in air electrode reactions, which could seriously decay the lifetime of air electrode materials. In this work, a very stable and efficient air electrode, SrEuFeCoO (SEFC) with layer structure, is designed and deployed in P-RSOCs. X-ray diffraction analysis and High-angle annular dark-filed scanning transmission electron microscopy images of SEFC reveal that Sr atoms occupy the center of perovskite slabs, whereas Eu atoms arrange orderly in the rock-salt layer. Such a special structure of SEFC largely depresses its Lewis basicity and therefore its reactivity with steam. Applying the SEFC air electrode, our button switches smoothly between both fuel cell and electrolysis cell (EC) modes with no obvious degradation over a 135 h long-term test under wet H (∼3% HO) and 10% HO-air atmospheres. A record of over 230 h is achieved in the long-term stability test in the EC mode, doubling the longest test that had been previously reported. Besides good stability, SEFC demonstrates great catalytic activity toward air electrode reactions when compared with traditional LaSrCoFeO air electrodes. This research highlights the potential of stable and efficient P-RSOCs as an important part in a sustainable new energy power system.

Substitution of anions such as F and Cl can effectively improve the stability of proton-conducting electrolytes at no expense to proton conduction. However, during operation, F and Cl in electrolytes can transfer to the cathodes, which reduces the stability of the electrolytes. In this work, F -doped Ba Sr Co Fe O [Ba Sr Co Fe O F (F-BSCF)] was prepared as a potential cathode for proton-conducting solid oxide fuel cells with BaCe Sm F O electrolyte. The incorporation of F in the cathode depressed F diffusion from the electrolyte and improved the stability of button cells. Temperature-changing X-ray photoelectron spectroscopy and electronic conductivity relaxation results demonstrated that the incorporation of F enhanced the oxygen incorporation kinetics at intermediate temperatures and improved the cathode catalytic performance. Moreover, a button cell prepared with this novel cathode was stable for 270 h at a current density of 300 mA cm and 700 °C, which was much superior than those containing a BSCF cathode.

The different working mechanisms for one cathode performing in both O- and P-SOFCs on the atomic scale.