Opportunities and Challenges in Materials Development for Thin Film Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are currently the focus of intense investigation given their high chemical-to-electrical energy conversion efficiency and low carbon footprint. In this review, the development of thin film SOFCs, sometimes described as 'micro-SOFCs', is highlighted and analysed. Opportunities for reduced temperature operation and portable power generation arise from the decreased thickness of the solid electrolyte, as well at the metastable phases and nanoscale-dependent effects that are a consequence of the reduced temperature of fabrication. Challenges such as enhanced cation diffusion along grain boundaries are; however, also observed, potentially impacting the long-term stability of these devices. Recent progress achieved in understanding these and other challenges are reviewed and directions for future work identified.