Parametric study on electrodeposition of a nanofibrous LaCoO3 SOFC cathode

Abstract

Solid oxide fuel cells (SOFCs) capable of operating at low to intermediate temperatures (600–750 °C) are vital for the development of robust SOFC power generation systems. In this regard, the oxygen reduction reaction is the rate-limiting step that requires new highly active catalysts or drastic improvements in the cathode microstructure when using the conventional cathode materials. Here, we report a parametric study on electrodeposition for synthesizing nanostructured cathodes for the SOFCs by producing a nanofibrous LaCoO3 cathode. The synthesis of the nanofibrous LaCoO3 involves preparing an electrically conductive template of carbon nanotubes onto the walls of a porous scaffold made of oxide-ion-conducting material followed by co-electrodeposition of La and Co hydroxides from an aqueous mixed-metal nitrate solution. Then, the deposited metal hydroxides are thermally converted to the LaCoO3 perovskite phase through low-temperature calcination performed at 800 °C. LaCoO3 microstructure is optimized as a function of deposition time, applied current, and solution concentration to obtain a nanofibrous morphology. Anode-supported SOFCs with the nanofibrous LaCoO3 cathode are tested for their electrochemical performance and durability. A durable performance obtained during the 200 h stability tests, performed at 750 and 800 °C and under a galvanostatic load of 1 A cm−2, shows the potential of the electrodeposition for producing robust nanostructured SOFC cathodes.