Multicomponent doping realized superior triple-conducting within cobalt-free Ruddlesden-Popper-type perovskite for Proton-conducting fuel cells cathode

Abstract

Proton-conducting solid oxide fuel cells (H-SOFCs) are appealing for low-to-intermediate temperature operation due to their intrinsic lower activation energy and better ionic conductivity. Unfortunately, there are currently few acceptable and high-performing cathode materials available for H-SOFCs. Herein, we present a novel high performance multicomponent Ruddlesden-Popper (RP) type cathode Pr3Ni1.5Cu0.3Nb0.05Ta0.05Zr0.05Y0.05O7-δ (PNCNTZY) with superior triple conducting property. The multicomponent co-doping of Nb, Ta, Zr, and Y brings about the enhancement of configurational entropy and cocktail effect for improving H+/O2-/e- triple conductivity and oxygen vacancy concentration. Naturally, the ORR activity is improved by facilitated charge transfer and oxygen surface exchange, exhibiting reduced polarization resistance to just 0.24 Ω cm2 at 550 °C. When used as the cathode in H-SOFC single cells, excellent power production is demonstrated at 550 °C, with a peak power density of up to 0.84 W cm-2. Furthermore, the PNCNTZY sample shows adequate thermal compatibility with proton conductor electrolytes BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) and then appropriate endurance durability (0.8 A cm-2 at 550 °C for about 250 h) due to their match of thermal expansion coefficient (TEC) brought about by the Co-free and partial replacement of larger-size elements. This extremely promising Co-free RP perovskite cathode for H-SOFCs produced by this work might provide a new type candidate and novel strategy for the commercialization of H-SOFCs.