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

Cubic perovskite SrCoO3−δ was successfully prepared through simple anion F-doping and demonstrated great OER performance.

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.

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CO2 was successfully converted to valuable products using P-SOECs, and the reaction mechanisms were discussed.

An equivalent circuit has firstly been proposed to evaluate proton-conducting electrolysis cells for their intrinsic electrode performance concealed by electronic conduction in electrolyte.

Driven by the mounting concerns on global warming and energy crisis, intermediate temperature solid-oxide fuel cells (IT-SOFCs) have attracted special attention for their high fuel efficiency, low toxic gas emission, and great fuel flexibility. A key obstacle to the practical operation of IT-SOFCs is their sluggish oxygen reduction reaction (ORR) kinetics. In this work, we applied a new two-layered Ruddlesden-Popper (R-P) oxide, Sr3Fe2O7-δ (SFO), as the material for oxygen ion conducting IT-SOFCs. Density functional theory calculation suggested that SFO has extremely low oxygen ion formation energy and considerable energy barrier for O(2-) diffusion. Unfortunately, the stable SrO surface of SFO was demonstrated to be inert to O2 adsorption and dissociation reaction, and thus restricts its catalytic activity toward ORR. Based on this observation, Co partially substituted SFO (SFCO) was then synthesized and applied to improve its surface vacancy concentration to accelerate the oxygen adsorptive reduction reaction rate. Electrochemical performance results suggested that the cell using the SFCO single phase cathode has a peak power density of 685 mW cm(-2) at 650 °C, about 15% higher than those when using LSCF cathode. Operating at 200 mA cm(-2), the new cell using SFCO is quite stable within the 100-h' test.