Nanofabrication technologies for low-temperature solid oxide cells: a comprehensive review of techniques, challenges, and future perspectives

Solid oxide cells (SOCs) are pivotal for renewable energy storage and conversion. They operate in two key modes: solid oxide electrolysis cells (SOECs) efficiently transform electrical power into fuel, while solid oxide fuel cells (SOFCs) convert fuel back into power. Conventional SOC fabrication relies on high-temperature sintering, leading to microstructured components that limit performance at reduced operating temperatures. Nanostructured electrodes and electrolytes are essential to enhance electrochemical activity (e.g., oxygen reduction and hydrogen evolution reactions) and ion transport rates at low temperatures, thereby addressing challenges such as material degradation and sealing reliability under high-temperature operation. This review systematically examines advanced nanofabrication techniques for SOCs, including infiltration, exsolution, electrospinning, template-assisted synthesis, self-assembly, vapor deposition, high-pressure compaction, and sintering-free direct assembly. For each method, we analyze the process-microstructure-performance relationships, alongside comparative assessments of cost, scalability, complexity, and technological maturity. Furthermore, we critically evaluate the current limitations and future prospects of SOC nanofabrication, providing insights for next-generation energy technologies.