Gu Young Cho

Plasma-Enhanced Atomic Layer Deposition of Nanoscale Yttria-Stabilized Zirconia Electrolyte for Solid Oxide Fuel Cells with Porous Substrate

Nanoscale yttria-stabilized zirconia (YSZ) electrolyte film was deposited by plasma-enhanced atomic layer deposition (PEALD) on a porous anodic aluminum oxide supporting substrate for solid oxide fuel cells. The minimum thickness of PEALD-YSZ electrolyte required for a consistently high open circuit voltage of 1.17 V at 500 °C is 70 nm, which is much thinner than the reported thickness of 180 nm using nonplasmatic ALD and is also the thinnest attainable value reported in the literatures on a porous supporting substrate. By further reducing the electrolyte thickness, the grain size reduction resulted in high surface grain boundary density at the cathode/electrolyte interface.

Atomic layer deposition of ultrathin blocking layer for low-temperature solid oxide fuel cell on nanoporous substrate

An ultrathin yttria-stabilized zirconia (YSZ) blocking layer deposited by atomic layer deposition (ALD) was utilized for improving the performance and reliability of low-temperature solid oxide fuel cells (SOFCs) supported by an anodic aluminum oxide substrate. Physical vapor-deposited YSZ and gadolinia-doped ceria (GDC) electrolyte layers were deposited by a sputtering method. The ultrathin ALD YSZ blocking layer was inserted between the YSZ and GDC sputtered layers. To investigate the effects of an inserted ultrathin ALD blocking layer, SOFCs with and without an ultrathin ALD blocking layer were electrochemically characterized. The open circuit voltage (1.14 V) of the ALD blocking-layered SOFC was visibly higher than that (1.05 V) of the other cell. Furthermore, the ALD blocking layer augmented the power density and improved the reproducibility.

Properties of nanostructured undoped ZrO2 thin film electrolytes by plasma enhanced atomic layer deposition for thin film solid oxide fuel cells

Nanostructured ZrO2 thin films were prepared by thermal atomic layer deposition (ALD) and by plasma-enhanced atomic layer deposition (PEALD). The effects of the deposition conditions of temperature, reactant, plasma power, and duration upon the physical and chemical properties of ZrO2 films were investigated. The ZrO2 films by PEALD were polycrystalline and had low contamination, rough surfaces, and relatively large grains. Increasing the plasma power and duration led to a clear polycrystalline structure with relatively large grains due to the additional energy imparted by the plasma. After characterization, the films were incorporated as electrolytes in thin film solid oxide fuel cells, and the performance was measured at 500 °C. Despite similar structure and cathode morphology of the cells studied, the thin film solid oxide fuel cell with the ZrO2 thin film electrolyte by the thermal ALD at 250 °C exhibited the highest power density (38 mW/cm2) because of the lowest average grain size at cathode/electro...

Surface engineering of nanoporous substrate for solid oxide fuel cells with atomic layer-deposited electrolyte

Summary Solid oxide fuel cells with atomic layer-deposited thin film electrolytes supported on anodic aluminum oxide (AAO) are electrochemically characterized with varying thickness of bottom electrode catalyst (BEC); BECs which are 0.5 and 4 times thicker than the size of AAO pores are tested. The thicker BEC ensures far more active mass transport on the BEC side and resultantly the thicker BEC cell generates ≈11 times higher peak power density than the thinner BEC cell at 500 °C.

PEALD YSZ-based bilayer electrolyte for thin film-solid oxide fuel cells

Yttria-stabilized zirconia (YSZ) thin film electrolyte deposited by plasma enhanced atomic layer deposition (PEALD) was investigated. PEALD YSZ-based bi-layered thin film electrolyte was employed for thin film solid oxide fuel cells on nanoporous anodic aluminum oxide substrates, whose electrochemical performance was compared to the cell with sputtered YSZ-based electrolyte. The cell with PEALD YSZ electrolyte showed higher open circuit voltage (OCV) of 1.0 V and peak power density of 182 mW cm(-2) at 450 °C compared to the one with sputtered YSZ electrolyte(0.88 V(OCV), 70 mW cm(-2)(peak power density)). High OCV and high power density of the cell with PEALD YSZ-based electrolyte is due to the reduction in ohmic and activation losses as well as the gas and electrical current tightness.

Experimentation and modelling of nanostructured nickel cermet anodes for submicron SOFCs fuelled indirectly by industrial waste carbon

Nickel-Samaria Doped Ceria (Ni-SDC) cermet anodic thin films of about 500 nm were prepared on Scandia Stabilized Zirconia (ScSZ) electrolyte supports via reactive radio frequency (RF) sputtering. Anode deposition was done at room temperature, and the background sputtering gas was a reactive mixture of Ar : O2/80 : 20. The oxide conducting fuel cell configuration was completed by screen printing of lanthanum strontium manganite (LSM/YSZ) cathodes on the other side of the ScSZ supports. High resolution transmission electron microscopy (HR-TEM) of the cermet anode revealed an arranged nanostructure, with patterned ceria enclosing the nickel molecules in porous media. These highly ordered anodes were tested under (i) H2 and (ii) a product fuel of CO2 electro-reduced via industrial waste carbon (IWC). IWC fuel performance matched the H2 fuel performance in terms of peak power density and longevity, with an added lower fuel cost advantage. HR-TEM and scanning electron microscope (SEM) 2D images were utilized to simulate the reaction kinetics of the nanostructured porous thin film cermet anode. The reported high electrochemical performance was proved to result from the high density of triple-phase boundaries, arranged nanostructure and high contiguity of the special design of the nano-anodes. Experimental and simulation results were coherent with each other, especially for IWC operated SOFCs working at or above 700 °C.