Atomic Layer Deposition to Design Internal Surface of Porous Electrode for Accelerating Charge and Mass Transfer in Fuel Cells

Abstract

The inadequate catalytic activity and conductivity from the porous electrode hinder the power density of the ceramic fuel cells operated at high temperatures. For the first generation Solid Oxide Fuel Cells (SOFCs) with yttria stabilized zirconia (YSZ) electrolyte, the present work employs atomic layer deposition (ALD) and implanted nanoscale eletrocatalysts on the internal surface of the composite cathode consisting lanthanum strontium manganite and YSZ. Upon electrochemical operation, the ALD layer with optimized nanostructure develops into a nano-porous uniform and conformal heterostructured electrochemical active percolating network, provides additional charge and mass transfer pathways, and subsequently extends the electrochemical active area from the original localized triple phase boundaries (TPBs) to the entire internal surface of porous cathode. For the as-fabricated commercial SOFCs, such ALD coating of LSM/YSZ cathode resulted in a large reduction of cell polarization resistance by up to over 50 % and an enormous increase of cell peak power density by over 300 %, which is significantly outperforming that of the state-of-the-art SOFCs with mixed ionic and electronic conducting cathode.