Advanced Cathode Materials for Protonic Ceramic Fuel Cells: Recent Progress and Future Perspectives

Abstract

Intermediate‐temperature proton ceramic fuel cells (PCFCs)–a promising power generation technology–have attracted significant attention in recent years because of their unique advantages over conventional high‐temperature solid oxide fuel cells and low‐temperature proton exchange membrane fuel cells. The cathodes of PCFCs simultaneously require efficient channels for proton, oxide‐ion, and electron transfer; therefore, designing and engineering cathode materials with tailorable H+, O2−, and e− conductivities are crucial for improving PCFC performance. Despite significant efforts and critical progress in this field, exploring the desired cathode materials remains challenging. This review provides a comprehensive and critical overview of oxide materials for PCFC cathodes, particularly triple H+/O2−/e− conductors. Their proton uptake, conduction mechanisms, and structure–property relationships are focused on to guide future material design. In addition, the electrochemical performance of these cathode materials in PCFCs is discussed and the electrochemical performance gaps among PCFCs with different types of cathode materials are defined. Finally, perspectives on the development of high‐performance PCFCs are proposed.

Durable and High-Performance Thin-Film BHYb-Coated BZCYYb Bilayer Electrolytes for Proton-Conducting Reversible Solid Oxide Cells

“…In comparison, PBCC|BZCY­Yb1711|Ni-BZC­YYb1711 cells reported by Zhou et al, which are nearly identical cells (including the same BZCYYb1711 electrolyte thickness of 10 μm) without the BHYb82 protection layer, achieved 1.58, 1.06, and 0.66 W cm –2 at 650, 600, and 550 °C. Thus, the performance of the bilayer-based cells is comparable to that of the unmodified cells and demonstrated state-of-the-art peak power densities exceeding previously reported P-ReSOCs . Additionally, the peak power density exceeds that of similar bilayer-based P-ReSOCs, as shown in Table .…”

Realizing Metastable Cobaltite Perovskite via Proton-Induced Filling of Oxygen Vacancy Channels

“…Such a water-uptake reaction by oxygen vacancies has been established in many proton-conducting oxides 39 and applied to PCFCs. 40,41 After the structural relaxation by firstprinciples calculation, it is predicted that HSrCoO 3 has a perovskite structure with a distorted [CoO 6 ] octahedral framework (Figure 4c). In this scenario, the inverse transformation from M-SCO to B-SCO under vacuum can be easily explained due to the dehydration process.…”

A mini review of the recent progress of electrode materials for low-temperature solid oxide fuel cells

“…However, such a high operating temperature limits material selection and raises manufacturing and maintenance costs. 1 It may result in the electrodes coarsening and performance degradation. The grain coarsening and electrode expansion would affect the chemical and thermal stability of the cell and stack components, causing their failure.…”

“…There are two main approaches to improve the electrochemical performance of low-temperature SOFCs (LT-SOFCs) to meet the requirements of commercialization (B1 W cm À2 at 650 1C), including (1) reducing the thickness of the dense electrolyte layer to shorten the mass transfer distance; (2) and developing high-performance electrode materials with high catalytic activity and specific microstructure, especially for cathodes, as the oxygen dissociation reactions accompanied with higher activation energy occur on their surface. In recent years, there have been many reviews on electrode materials' modification for low-temperature solid oxide fuel cells.…”