Effect of Electrolyte Thickness of Thin Film Solid Oxide Fuel Cell on Nanostructure and Performance

Abstract

Advances in nanotechnology have enabled solid oxide fuel cells to perform high-efficiency energy conversion at lower operating temperatures than before. In particular, the thin film electrolyte can effectively offset the drop in ion conductivity at a low operating temperature due to a reduced ion path. In this study, the performance difference of solid oxide fuel cells according to the thickness of these thin film electrolytes was compared. Thin film solid oxide fuel cells were fabricated with YSZ electrolytes of 3.3 μm, 4.0 μm, and 4.7 μm thickness using different sputtering deposition times. First, the thickness of the electrolyte affected the gas tightness. The OCV of the cell using the 3.3 μm, 4.0 μm, and 4.7 μm thick electrolyte showed 1.01 V, 1.03 V and 1.05 V respectively. As the sputter deposition time increased, the surface grain size of the YSZ electrolyte also increased, affecting both the electrolyte's ohmic and the electrode's polarization resistance. Therefore, the difference in the thickness of the electrolyte showed a dramatic difference in performance. The cells with 3.3 μm, 4.0 μm, and 4.7 μm thick electrolytes showed performances of 193 mW/cm², 99 mW/cm², and 57 mW/cm², respectively at 500 °C.