Solid electrolytic capacitors
View Patent ↗A solid electrolytic capacitor is disclosed. The capacitor comprises an organophosphorus material positioned between the dielectric layer and the polymeric electrolyte layer. The organophosphorus compound improves the interlayer adhesion between the dielectric and electrolyte layers.
1. A solid electrolytic capacitor comprising:
(a) an anode,
(b) a dielectric material covering the surface of the anode,
(c) a layer of an organophosphorus material at least partially covering the dielectric layer, wherein the organo group of the organophosphorus material is a π conjugated oligomer or polymer, and
(d) a layer of a conductive polymer at least partially covering layer (c).
2. The electrolytic capacitor of claim 1 wherein the conductive polymer layer is a π conjugated polymer.
3. The electrolytic capacitor of claim 2 in which the π conjugated polymer layer (d) and the π conjugated oligomeric or polymeric subsistent of the organophosphorus material are derived from the same monomers.
4. The electrolytic capacitor of claim 3 in which the monomeric units are based on thiophene.
5. The electrolytic capacitor of claim 1 wherein the anode is a valve metal.
6. The electrolytic capacitor of claim 5 wherein the valve metal is selected from aluminum, niobium, tantalum, silicon and titanium.
7. The electrolytic capacitor of claim 5 wherein the dielectric material is a valve metal oxide.
8. The electrolytic capacitor of claim 1 in which the organophosphorus material is bonded to the dielectric layer.
9. The electrolytic capacitor of claim 1 in which the organophosphorus material is derived from an organophosphorus acid or a derivative thereof.
10. The electrolytic capacitor of claim 1 in which the conductive polymer is selected from polyaniline, polythiophene, polypyrrole, polyacetylene, polyphenylene and poly(p-phenylene-vinylene).
11. The electrolytic capacitor of claim 1 in which the layer of conductive polymer serves as the cathode.
12. The electrolytic capacitor of claim 1 which has a graphite-silver cathode layer at least partially covering layer (d).