Properties and synthesis of ultra-thin SOFC structures

This paper presents an initial exploration of the use and possibility of nm thin SOFC electrolyte structures to enhance cell performance. This is addressed, on one hand, by analyzing the extent of interfacial space-charge areas at the electrode-electrolyte interface. A simple thermodynamic treatment shows that such areas have a characteristic dimension in the order of 0.2 nm so that they can be classified as 2D interfacial effects and will not affect bulk electrolyte behavior. The characteristic dimensions may appear to be larger in more advanced treatments of restricted statistical distribution of charge carriers over the electrolyte lattice. On the other hand it is shown that 10 nm thin, dense zirconia layer can be prepared, here by spin coating of <10 nm spherical zirconia particles onto silicon substrates, followed by O2 plasma treatment and annealing at 600oC. This unconventional strategy can also be used to realize foreseen, ideal graded electrode structures, in combination with thin electrolytes.