High power density thin film SOFCs with YSZ/GDC bilayer electrolyte

Bilayer electrolytes composed of a gadolinium-doped CeO2 (GDC) layer (∼6 μm thickness) and an yttria-stabilized ZrO2 (YSZ) layer with various thicknesses (∼330 nm, ∼440 nm, and ∼1 μm) were deposited by a pulsed laser deposition (PLD) technique for thin film solid oxide fuel cells (TFSOFCs). The bilayer electrolytes were prepared between a NiO–YSZ (60:40 wt.% with 7.5 wt.% carbon) anode and La0.5Sr0.5CoO3–Ce0.9Gd0.1O1.95 (50:50 wt.%) composite cathode for anode-supported single cells. Significantly enhanced maximum power density was achieved, i.e., a maximum power density of 188, 430, and 587 mW cm−2 was measured in a bilayer electrolyte single cell with ∼330 nm thin YSZ at 650, 700, and 750 °C, respectively. The cell with the bilayer electrolyte (YSZ ∼330 nm) doubles the overall power output at 750 °C compared to that achieved in the GDC single layer cell. This signifies that the YSZ thin film serves as a blocking layer for preventing electrical current leakage in the GDC layer and also provides chemical, mechanical, and structural integrity in the cell, which leads to the overall enhanced performance.

. A: Cross-sectional TEM images show a GDC single layer and YSZ/GDC bilayer electrolyte structures. As clearly observed from TEM images, the YSZ interlayer thickness varies from ∼330 nm to ∼1 μm. B: The cell with the bilayer electrolyte (YSZ ∼330 nm) doubles the overall power output at 750 oC compared to that achieved in the GDC single layer cell.Figure optionsDownload as PowerPoint slideHighlights
► YSZ/ GDC bilayer thin film electrolytes were deposited by a pulsed laser deposition (PLD) technique.
► Thin YSZ film as a blocking layer effectively suppresses the cell voltage drop without reducing the ionic conductivity of the electrolyte layer.
► The YSZ/ GDC bilayer structure presents a feasible architecture for enhancing the overall power density and enabling chemical, mechanical, and structural stability in the cells.