Reduced‐Temperature Solid Oxide Fuel Cell Based on YSZ Thin‐Film Electrolyte

A planar thin‐film solid oxide fuel cell has been fabricated with an inexpensive, scalable, technique involving colloidal deposition of yttria‐stabilized zirconia (YSZ) films on porous NiO‐YSZ substrates, yielding solid oxide fuel cells capable of exceptional power density at operating temperatures of 700 to 800°C. The thickness of the YSZ film deposited onto the porous substrate is approximately 10 μm after sintering, and is well bonded to the NiO/YSZ substrate. Ni‐YSZ/YSZ/LSM cells built with this technique have exhibited theoretical open‐circuit potentials (OCPs), high current densities, and exceptionally good power densities of over 1900 mW/cm 2 at 800°C. Electrochemical characterization of the cells indicates negligible losses across the Ni‐YSZ/YSZ interface and minor polarization of the fuel electrode. Thin‐film cells have been tested for long periods of time (over 700 h) and have been thermally cycled from 650 to 800°C while demonstrating excellent stability over time.