Highly enhanced electrochemical performance of silicon-free platinum–yttria stabilized zirconia interfaces

Abstract

In the drive to achieve economically viable solid oxide fuel cells, efforts have been directed towards substantially decreasing their operating temperature. Unfortunately, these efforts have been hindered by extremely sluggish electrode kinetics at reduced temperatures. In this report, we show that silicon impurities on the surface of the electrolyte play a critical role in influencing electrode kinetics. More specifically, improvements by as much as three orders of magnitude are reported for the performance of platinum electrodes on yttria-stabilized zirconia electrolytes prepared as high purity thin films with a largely Sifree surface. These improvements in performance are estimated to enable operation of a solid oxide fuel cell down to approximately 400°C.

The effect of loading and particle size on the oxygen reaction in CGO impregnated Pt electrodes

“…Silicate impurities segregate to the surface during high temperature sintering [29,30] and are known to inhibit the electrochemical properties of the platinum electrode by blocking the oxygen reaction [31]. If the impurities are deposited at the TPB, as shown in Fig.…”

Microstructure and Microfabrication Considerations for Self‐Supported On‐Chip Ultra‐Thin Micro‐Solid Oxide Fuel Cell Membranes

“…This is especially crucial since the oxygen surface exchange that occurs on cathode surfaces is responsible for the majority of voltage loss in SOFCs and avoiding Si or other impurities is critical [22]. Therefore, when developing LSCF-YSZ membranes for Si-based lSOFCs, we deposited 75 nm YSZ first then 63 nm LSCF on Si 3 N 4 -coated Si substrates.…”

“…(ii) Since LSCF-YSZ membranes are released from Si 3 N 4 prior to any HT treatment, they are thus not subject to the high thermal stresses caused by Si 3 N 4 and are likely to have more room in temperaturestress design space to resist buckling failure, albeit thinner films are more susceptible to tensile failure. (iii) Moreover, the likelihood of forming an interfacial layer between YSZ and Si 3 N 4 and poisoning by Si [22] are greatly minimised.…”

“…A grand challenge for current lSOFCs development is to realise reliable, self-supported CEA membranes with maximum active area [5], while avoiding processing-related contamination and damage at the same time [22], since power output scales with active area for the electrochemical reactions. Self-supported CEA membranes that have been reported are still in the range of few hundreds of lm [6,8,9].…”

“…These efforts lead us to make several conclusions on microstructure-related guidelines when designing CEA membranes. Moreover, microfabrication procedures for membranes that minimise possible Si-poisoning [22] and formation of reaction layers at interfaces were introduced. Finally, self-supported large-area CEA membranes are demonstrated.…”