A nanocrystalline La0.6Sr0.4Co0.4Fe0.6O3−δ interlayer for an enhanced oxygen electrode–electrolyte interface in solid oxide cells

Abstract

A catalytically active and intimate interface between the electrode and electrolyte is crucial for the performance of solid oxide cells (SOCs). Here, we show that the nanocrystalline La_0.6Sr_0.4Co_0.4Fe_0.6O_3−δ (LSCF) functional interlayer fabricated by the sputtering process establishes an active and mechanically stable oxygen electrode/electrolyte interface and thereby reduces contact resistance with improving electrolysis cell (EC) durability. The LSCF interlayer with a thickness of over 100 nm enlarged the active electrochemical region, containing finely nanostructured grains and grain boundaries. This enhances ion transport and ionic charge transfer kinetics at the interface, resulting in threefold higher maximum power density in fuel cell (FC) mode and fourfold greater current density in EC mode compared with those in the reference cell at 650 °C. The EC durability test revealed a little cell voltage difference at 650 °C for 100 h. We clearly demonstrate that the precise control of the nanoscale morphology and crystallinity of the LSCF interlayer by thin-film deposition is important for developing high-performance thermally stable SOCs.