Computational Predictions of Upscaling Solid Oxide Electrochemical Reactor Performances By Pillared Electrolyte | Electrode Interfaces

Abstract

Increasing densities of electrode | electrolyte interfacial areas (and triple phase boundaries) of solid oxide fuel cells or electrolyzers (solid oxide electrochemical reactors, SOERs) offers one means of increasing performance, reproducibility and potentially decreasing cost. Three-dimensional (3D) structuring of those interfaces can be achieved by 3D printing, but modelling is required to optimize geometries. Using kinetic parameter values from the literature, COMSOL finite element software was used to predict effects of YSZ electrolyte (c.f. electrode) pillar geometries on SOER performance, relative to planar YSZ electrolytes. The modified geometries are based on yttria-stabilized zirconia (YSZ) electrolyte pillars on top of < 10 mm thick planar YSZ electrolyte, thereby increasing interfacial to geometric area ratios. Electrolyte layers have been inkjet printed on Ni(O)-YSZ substrate negative electrode precursors and porous lanthanum strontium manganite (LSM) positive electrode have been printed over the YSZ, after sequential sintering producing complete SOERs: H2O-H2 | Ni(O)-YSZ | YSZ-YSZ pillars | YSZ-LSM | LSM | O2.Results will be reported showing that despite interfacial electrode | electrolyte areas being up scaled by factors of 10-100 - depending on pillar diameter (5-50 mm) and height (15-150 mm) - current densities were predicted to increase by only 70-100% due to increased current path length along the pillars, which increases ohmic potential loss relative to the faradaic impedance. Hence, predictions of enhancement depend strongly on the kinetic parameters of the electrode material.