Protonic Ceramic Fuel Cell with Bi-Layered Structure of BaZr0.1Ce0.7Y0.1Yb0.1O3–δ Functional Interlayer and BaZr0.8Yb0.2O3–δ Electrolyte

Widespread application of PCFCs will require higher performance even at lower temperatures (<600 °C). This paper reports development of a protonic ceramic fuel cell (PCFC) with a bi-layered proton-conducting phase structure consisting of a BaZr0.1Ce0.7Y0.1Yb0.1O3–δ (BZCYYb1711) functional interlayer and BaZr0.8Yb0.2O3–δ (BZYb20) electrolyte. In this PCFC, a zirconate-based oxide with high durability against CO2, BZYb20, is selected as the electrolyte material, and a BZCYYb1711 functional interlayer is applied between the dense BZYb20 electrolyte and a cathode to achieve higher power density and higher open-circuit voltage (OCV) of the PCFC. In cell fabrication via conventional wet process and co-sintering, although Ni diffusion occurs from NiO-BZYb20 anode into the approximately 8-µm-thick BZYb20 electrolyte, almost no Ni diffuses into the BZCYYb1711 functional interlayer. Compared to a PCFC without this functional interlayer, the proposed PCFC exhibits higher electrochemical performance. Results showed that the BZCYYb1711 functional interlayer reduces cathode polarization resistance and increase power density of the PCFC. Moreover, the OCV increases because the BZCYYb1711 functional interlayer suppresses the current leakage caused by hole conduction of the BZYb20 electrolyte. In conclusion, this bi-layered structure effectively improves both the power density and OCV of PCFCs.