Reversible protonic ceramic cells (RePCCs) can facilitate the global transition to renewable energy sources by providing high efficiency, scalable, and fuel‐flexible energy generation and storage at the grid level. However, RePCC technology is limited by the lack of durable air electrode materials with high activity toward the oxygen reduction/evolution reaction and water formation/water‐splitting reaction. Herein, a novel nanocomposites concept for developing bifunctional RePCC electrodes with exceptional performance is reported. By harnessing the unique functionalities of nanoscale particles, nanocomposites can produce electrodes that simultaneously optimize reaction activity in both fuel cell/electrolysis operations. In this work, a nanocomposite electrode composed of tetragonal and Ruddlesden–Popper (RP) perovskite phases with a surface enriched by CeO2 and NiO nanoparticles is synthesized. Experiments and calculations identify that the RP phase promotes hydration and proton transfer, while NiO and CeO2 nanoparticles facilitate O2 surface exchange and O2‐ transfer from the surface to the major perovskite. This composite also ensures fast (H+/O2‐/e‐) triple‐conduction, thereby promoting oxygen reduction/evolution reaction activities. The as‐fabricated RePCC achieves an excellent peak power density of 531 mW cm‐2 and an electrolysis current of −364 mA cm‐2 at 1.3 V at 600 °C, while demonstrating exceptional reversible operation stability of 120 h at 550 °C.

Research data are not shared.

No abstract

Proton-conducting fuel cells (PCFCs) with a perovskite-type proton-conducting electrolyte show many advantages over conventional oxygen-ion-conducting ceramic fuel cells. Both electrode catalytic activity and electrolyte conductivity determine the performance of PCFCs. Cation non-stoichiometry has a great influence on the catalytic activity and conductivity of perovskite oxides. Here, we propose a PCFC with B-site-cation-deficient perovskites (BCDPs) for all cell components, including cathode, electrolyte, and anode. More specifically, a cell with Ba­(Co0.4Fe0.4Zr0.1Y0.1)0.95O3−δ (BCFZY-0.95) cathode, Ba­(Zr0.1Ce0.7Y0.1Yb0.1)0.95O3−δ (BZCYYb-0.95) electrolyte, and Ni–BZCYYb-0.95 anode is fabricated and tested for power generation. Electrochemical impedance spectroscopy in combination with the distribution of relaxation times verify the superior oxygen reduction reaction activity of the BCFZY-0.95 cathode compared to BaCo0.4Fe0.4Zr0.1Y0.1O3−δ and higher proton conductivity of BZCYYb-0.95 than BaZr0.1Ce0.7Y0.1Yb0.1O3−δ. At 650 °C, a BCDP cell with a thin-film electrolyte shows a high-power density of 840 mW cm–2. The cell is stably operated within the test period of 400 h of stability at 550 °C.

No abstract