Yeageun Lee

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.

Integrated design of a Ni thin-film electrode on a porous alumina template for affordable and high-performance low-temperature solid oxide fuel cells

Nanostructured Ni thin films, with high porosity, are fabricated by DC sputtering on an anodic aluminum oxide template as an active anode for low-temperature solid oxide fuel cells with a target operating temperature of 500 °C. To maximize the electrode performance, we control their effective electrical conductivity and microstructure by varying the sputtering parameters (e.g., the deposition pressure and time) and investigate the gas permeability, sinterability, as well as the ohmic and polarization resistances by a range of analysis techniques, in this case SEM, TEM, mass spectrometry, the four-point probe method and AC impedance spectroscopy. We observe that the thicker the Ni film, the higher the effective electrical conductivity and the lower the sheet resistance, while the thinner the film, the better the gas permeability and electrochemical activity for H2 electro-oxidation. These tradeoffs are quantitatively computed for cell dimensions and area specific resistances, thus suggesting an optimal design for affordable and high-performance electrodes.