Core-Shell Nanofiber Composites As Highly Active and Robust Anodes for Direct-Hydrocarbon Fueled Solid Oxide Fuel Cells

Abstract

Direct use of methane in solid oxide fuel cells (SOFCs) can be a key to realize the high-efficiency advantage of fuel cell technologies before mature hydrogen economy. One of the most critical issues for direct-methane SOFCs is to prevent anode, particularly Ni-based, from carbon deposition (coking) that drastically degrades performance. A number of ceramic anodes have been developed to exhibit excellent coking resistance but their application is still limited by relatively low electrochemical activity. Impregnating catalytically active and high oxygen ion-conducting materials such as doped ceria to form nanoscale composites, some ceramic anodes demonstrated enhanced activity comparable to Ni-based anodes. However, fabrication methods employed so far require repetitive series of a coating and high-temperature calcination step to optimize the performance, which detrimentally affects nanoarchitectures. To address this issue, we demonstrate electrospinning as efficient route to prepare nanocomposite ceramic anodes. We successfully achieve highly active and robust anodes based on core-shell-like La0.75Sr0.25Cr0.5Mn0.5O3@Sm0.2Ce0.8O1.9 nanofibers through co-electrospinning method. Such nanoscale morphologies are maintained by the durable ceria shells at elevated temperature. Compared to the traditionally mixed counterpart, it shows nearly a half polarization resistance due to the increased active reaction sites and high stability in a wet methane at 700℃ for about 100 h.