Fabrication and electrochemical properties of cathode-supported solid oxide fuel cells via slurry spin coating

A cathode-supported SOFC consisting of LSM (La0.8Sr0.2MnO3−δ) cathode supporter, LSM–Sm0.2Ce0.8O2−δ (SDC) cathode functional layer (CFL), yttria stabilized zirconia (YSZ)/SDC bi-layered electrolyte and Ni-YSZ anode layer was fabricated by a slurry spin coating technique. The influence of the porosity in both the CFL and cathode supporter on the electrochemical properties of the cells has been investigated. It was found that properly controlling the porosity in the CFL would improve the performance of the cells using O2 in the cathode side (O2-cells), with a maximum power density (MPD) value achieving as high as 0.58 W cm−2 at 850 °C. However, this improvement is not so evident for the cells using air in the cathode side (air-cells). When increasing the porosity in the cathode-supporter, a significant increase of the power density for the air cells due to the decreasing Rconc,cRconc,c (cathode concentration polarization to the cell resistance) can be ascertained. In terms of our analysis on various electrochemical parameters, the Ract (activation polarization to the cell resistance) is assumed to be mainly responsible for the impedance arcs measured under the OCV condition, with a negligible Rconc,cRconc,c value being able to be detected in our impedances. In this case, a significant decreasing size of the impedance arcs due to the increasing porosity in the cathode supporter would correspond to a decrease of the Ract values, which was proved to be induced by the decreasing Rconc,cRconc,c.

► LSM cathode-supported cell prepared by slurry spin coating.
► Optimizing porosity in CFL resulting in power density of 0.58 W cm−2 at 850 °C.
► Activation polarization govern the impedance arcs measured under the OCV condition.
► Concentration polarization can induce the change of activation polarization.
► Four kinds of polarizations of our cells are separated and investigated.