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.

Graphical abstract. 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 full-size imageDownload 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.