Electrode materials for reversible solid oxide cells: A review and outlook

Reversible solid oxide cells (RSOCs) are an energy conversion technology capable of efficiently and flexibly converting electrical energy into chemical energy and vice versa, holding significant application potential in establishing a carbon-neutral energy system dominated by renewable energy. This article systematically reviews recent research progress on electrode materials in oxide-ion conducting RSOCs (O-RSOCs) and proton-conducting RSOCs (P-RSOCs), with a focused discussion on both fuel and oxygen electrode materials. Regarding fuel electrodes, it elaborates on the structural characteristics and performance advantages of nickel-based, copper-based, and perovskite oxide materials, while also addressing their challenges and improvement strategies concerning issues such as carbon deposition and sulfur poisoning. For the oxygen electrode, the progress on single perovskite, double perovskite, and Ruddlesden-Popper (RP) perovskite materials in O-RSOCs or P-RSOCs is critically assessed. To achieve both efficient oxygen reduction/evolution reactions (ORR/OER) and long-term operational stability, systematic optimization of perovskite electrodes is essential. Furthermore, the advantages and development potential of symmetric electrode materials are explored. Finally, future research directions for electrode materials of RSOCs are outlined, including intelligent materials design and microstructural control, in-depth investigation of degradation mechanisms, and deeper integration with renewable energy systems. This review aims to provide insights for advancing the practical application and industrial development of RSOCs technology. • The latest progress of RSOCs electrode materials, including fuel, oxygen and symmetric electrodes is reviewed. • The performance advantages, core challenges and optimization strategies of typical electrode materials are analyzed. • The future research directions focusing on intelligent material design, degradation mechanism analysis and integration with renewable energy system are proposed. • The insights for advancing the practical application and industrial development of RSOCs technology are offered.