Rational design of PrBaFe <sub>2</sub>O <sub>6− <i>δ</i> </sub>-based cathodes for protonic ceramic fuel cells
Yanru Yin, Shiqi Zhang, Ao Wang, Yan Dong, Jian Li, Lichao Jia
Abstract
Obtaining high-performance cathodes is critical for protonic ceramic fuel cells (PCFCs), as cathode performance significantly impacts fuel cell performance. A full understanding of the interactions among the diverse properties of cathode materials would benefit cathode design. In this study, PrBaFe<sub>2</sub>O<sub>6<i>−δ</i></sub> (PBF) was doped with various dopants, including cobalt (Co), Ni, Cu, Zn, and Mn. Experiments and first-principles calculations are used to study the key properties of dopant-modified PrBaFe<sub>2</sub>O<sub>6<i>−δ</i></sub>, including oxygen vacancy (V<sub>O</sub>) creation, hydration ability, proton mobility, and oxygen reduction reaction (ORR) activity. There is no perfect dopant that can improve every property to its full potential. Instead, different dopants can impact different properties of the material. Co-dopant has the best cathode performance since it balances the material’s instinctive properties, even though it does not provide a significant advantage in the formation of V<sub>O</sub>. PCFC utilizing Co-doped PrBaFe<sub>2</sub>O<sub>6<i>−δ</i></sub> cathode has a high performance of 1680 mW·cm<sup>−2</sup> at 700 °C, which is greater than that of the other dopant-tailored PrBaFe<sub>2</sub>O<sub>6<i>−δ</i></sub> cathodes reported in this study and is one of the largest ever recorded for PrBaFe<sub>2</sub>O<sub>6<i>−δ</i></sub>-based cathodes for PCFCs. Co-doped PrBaFe<sub>2</sub>O<sub>6<i>−δ</i></sub> cathode is further demonstrated to be robust, with excellent operational stability. This study not only provides a potential cathode candidate for PCFCs but also suggests an intriguing approach to cathode design by carefully examining and balancing different vital properties of the material.