Self-Assembled Triple-Conducting Nanocomposite as a Superior Protonic Ceramic Fuel Cell Cathode

By Yufei Song, Yubo Chen, Wei Wang, Chuan Zhou, Yijun Zhong, Guangming Yang, W. Zhou, Meilin Liu, Zongping Shao. Joule, 2019

454 citations recorded by the source corpus.

Protonic ceramic fuel cells (PCFCs) have attracted more attention than solid oxide fuel cells based on oxygen-ion-conducting electrolytes that operate at intermediate temperatures due to the lower activation energy for proton conduction than for oxygen ions in oxide electrolytes. However, the practical application of PCFC technology is hindered by the lack of suitable cathode materials. Here, we report our rationally designed triple conducting nanocomposite cathode BaCo(CeY)O- with sufficient oxygen ion-proton-electron transfer capability for PCFCs. This work develops the highly active and stable cathode material and simultaneously measures the specific values of oxygen ion, proton, and electron conductivity of the cathode material. This work also highlights the design strategy of perovskite-based electrocatalysts for other energy conversion and storage systems such as water splitting, metal-air batteries, and dye-sensitized solar cells.A nanocomposite cathode is composed of a mixed H/e conducting BaCeYCoO- (P-BCCY) phase, a mixed O/e conducting BaCoCeYO- (M-BCCY) phase, and a mixed O/e conducting BaCoO (BC) phase. The P-BCCY phase could promote proton diffusion, the M-BCCY phase could facilitate oxygen ion diffusion, and the BC phase could enhance the electronic conduction of the electrode; the interfaces between the three phases in nano-domain greatly increases the number of active sites for electrochemical reactions.Here, we report an oxygen ion-proton-electron-conducting nanocomposite, BaCo(CeY)O- (BCCY), derived from a self-assembly process, as a high-performance protonic ceramic fuel cell (PCFC) or mixed O/H dual-ion conducting fuel cell (dual-ion FC) cathode. Self-assembly during high-temperature calcinations results in the formation of a nanocomposite consisting of a mixed H/e conducting BaCeYCoO- (P-BCCY) phase and mixed O/e conducting BaCoCeYO- (M-BCCY) and BaCoO (BC) phases. The interplay between these phases promotes the oxygen reduction reaction (ORR) kinetics of this composite cathode and improves its thermo-mechanical compatibility by tempering the mismatch in thermal expansion coefficient (TEC). When tested as the cathode in anode-supported dual-ion FCs and PCFCs, peak power densities (PPDs) of 985 and 464 mW cm, respectively, are achieved at 650°C while maintaining a robust operational stability of 812 h at 550°C. This material is ideally suited for high-performance cathodes for PCFCs and dual-ion FCs, greatly accelerating the commercialization of this technology.

Subfields: Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/f58a0a866c5a507649b30f468d246ed2203895dd