BSCF/GDC as a refined cathode to the single-chamber solid oxide fuel cell based on a LAMOX electrolyte

Abstract

In an effort to build the solid oxide fuel cell for intermediate temperature operations, the oxide ion conductor member of LAMOX family appears to be an ideal candidate for electrolyte since its parent crystal La2Mo2O9 shows a monoclinic-cubic phase transition around 580°C. Nonetheless, members of the LAMOX family are much less refractory than the conventional electrode compositions which are targeted to coordinate with the electrolyte of yttrium stabilized zirconia. In this work, we study the viability of a cathode composite of Ba0.5Sr05Co0.8Fe0.2O3 (BSCF) and gadolinium doped ceria (GDC) to match the electrolyte La1.8Dy0.2Mo2O9 (LDM). Severe interfacial reactions between BSCF and LDM require a ceria-based diffusion barrier between them. The iron-doped GDC barrier of high sinterability is a convenient choice to block the unwanted reactions, allowing us to devise a BSCF/GDC composite cathode of gradient GDC content to relieve thermal stresses. The cell, operated in a mixed reactant chamber with flowing methane/air, functions properly at operation temperature 625–700°C. Its maximum power output is recorded at 675°C, since the BSCF crystal begins to degrade at 700°C under the methane/air atmosphere.