Electrode pattern for solid state ionic devices
View Patent ↗A solid oxide fuel cell electrode is stable during thermal cycling and includes a plurality of discrete geometric elements lightly packed on the electrolyte surface. Preferably, the geometric elements are regular hexagons, creating a “Thoneycomb” pattern electrode.
1. A solid oxide fuel cell comprising an electrode layer applied to an electrolyte layer wherein the electrode layer is not contiguous but rather is formed from a plurality of substantially discrete hexagonal elements separated by substantially linear and uniform gaps, such that adjacent hexagons have parallel edges, wherein the gaps take up less than about 2% of the surface area of the electrode.
2. A method of applying an electrode layer to an electrolyte layer in a SOFC comprising the steps of:
(a) providing a screen defining a pattern comprising a plurality of discrete elements;
(b) screen printing an electrode paste through the screen and onto the electrolyte such that the resulting electrode layer comprises a plurality of discrete elements that have a regular hexagonal shape and which are separated by substantially linear, uniform and narrow gaps, wherein the gaps take up less than about 5% of the surface area of the electrode, such that adjacent polygonal discrete elements have parallel edges and form a pattern comprising a honeycomb array of elements; and
(c) sintering the electrode layer.
3. The method of claim 2 further comprising the step of adding a contact paste layer over the electrode layer.
4. A solid oxide fuel cell comprising an electrode layer applied to an electrolyte layer wherein the electrode layer is discontinuous and comprises a plurality of substantially discrete polygonal elements that are hexagonal in shape separated by substantially uniform gaps, wherein the gaps take up less than about 5% of the surface area of the electrode, and wherein adjacent polygonal elements have parallel edges.
5. The solid oxide fuel cell of claim 4 wherein said hexagons are regular hexagons.
6. The solid oxide fuel cell of claim 4 further comprising a contact paste layer applied to the electrode layer.
7. The solid oxide fuel cell of claim 6 wherein the contact paste layer is a conducting ceramics including lanthanum cobaltate.
8. The solid oxide fuel cell of claim 7 wherein the contact paste layer is not sintered prior to use.
9. The solid oxide fuel cell of claim 4 wherein the gaps take up less then 2% of the surface area of the electrode.
10. The solid oxide fuel cell of claim 9 wherein the gaps take up less than about 1% of the surface area of the electrode.