A review of solid oxide cell technologies for power, fuel, and reversible energy storage

• SOCs enable efficient, flexible, and carbon–neutral energy conversion. • rSOCs offer bidirectional operation for grid balancing and energy storage. • SOECs offer high-efficiency hydrogen production via high-temperature electrolysis. • Advances in materials and design improve SOC performance and durability. • Challenges include degradation, scalability, and electrode stability. Solid oxide cell (SOC) technologies, encompassing solid oxide fuel cells (SOFCs), solid oxide electrolysis cells (SOECs), and reversible solid oxide cells (rSOCs), are emerging as key components in the transition to sustainable energy systems due to their high operating efficiency, fuel flexibility, carbon–neutral fuel production potential, and compatibility with renewable energy sources. This work reviews current SOC technologies for renewable electricity generation and sustainable fuel production, examining their working principles and system configurations. Recent advances in materials, stack design, and control strategies are reviewed alongside significant challenges in material stability, dynamic response, electrode degradation, thermal management, and scalability. The paper highlights demonstration projects and provides an economic feasibility analysis of each SOC technology. Among electrolysis technologies, SOEC has higher capital expenditure (CAPEX) and operational expenditures (OPEX), but lower hydrogen production costs. A Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis reveals that SOEC possesses high hydrogen production efficiency, while SOFC offers great flexibility in fuel usage. However, it also points out that thermal stress and component degradation are significant challenges that need to be addressed. For rSOC, the analysis highlights the advantages of flexibility for two-way operation, along with concerns about stack cell degradation. The review also identifies innovation pathways needed to transition these systems from advanced prototypes to reliable components of decarbonised energy infrastructure, focusing on cost-effective materials development, electrode optimisation, and enhanced mathematical modelling.