Enhanced Electrochemical Performance of a Ba0.5Sr0.5Co0.7Fe0.2Ni0.1O3−δ–BaZr0.1Ce0.7Y0.1Yb0.1O3−δ Composite Oxygen Electrode for Protonic Ceramic Electrochemical Cells

Abstract

The performance of protonic ceramic electrochemical cells (PCECs) is largely restricted by the slow oxygen reactions on the oxygen electrode. Herein, an active composite oxygen electrode Ba0.5Sr0.5Co0.7Fe0.2Ni0.1O3−δ–BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BSCFN–BZCYYb) with various mass ratios (6:4, 7:3, 8:2, and 9:1) is electrochemically investigated on fuel electrode-supported PCECs. BSCFN powder, with rich oxygen vacancies, shows a good chemical compatibility with BZCYYb electrolyte, as confirmed by the analyses of thermal gravimetric analysis and X-ray diffraction patterns. It is indicated that composite electrode with a ratio of 8:2 shows the best performance. For example, a peak power density (Pmax) of 1.14 W cm–2, an electrode polarization resistance (Rp) of 0.062 Ω cm2, and a reasonable durability test of 24 h at −0.5A cm–2 are delivered at 750 °C for the fuel cells with BSCFN–BZCYYb electrode with the ratio of 8:2. In addition, a stable operation (∼50 h) of cell with BSCFN–BZCYYb electrode (8:2 mass ratio) in dual modes of electrolysis and fuel cell (2 h for each mode) at ±0.5 A cm–2 is obtained, demonstrating a good reversibility.