High-Performance Proton-Conducting Fuel Cell with B‑Site-Deficient Perovskites for All Cell Components

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(Co_0.4Fe_0.4Zr_0.1Y_0.1)_0.95O_3−δ (BCFZY-0.95) cathode, Ba­(Zr_0.1Ce_0.7Y_0.1Yb_0.1)_0.95O_3−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 BaCo_0.4Fe_0.4Zr_0.1Y_0.1O_3−δ and higher proton conductivity of BZCYYb-0.95 than BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−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.