Solid electrolytic capacitor
A solid electrolytic capacitor comprising a capacitor element is provided. The capacitor element comprises a sintered porous anode body; a dielectric that overlies the anode body; and a solid electrolyte that overlies the dielectric and that includes a conductive polymer and a depolarizer.
1. A solid electrolytic capacitor comprising a capacitor element that comprises:
a sintered porous anode body;
a dielectric that overlies the anode body; and
a solid electrolyte that overlies the dielectric and that includes a conductive polymer and a depolarizer, wherein the depolarizer has a standard reduction potential of greater than 0.
2. The solid electrolytic capacitor of claim 1 , wherein the depolarizer is an aromatic quinone, nitroaromatic compound, or a combination thereof.
3. The solid electrolytic capacitor of claim 2 , wherein the depolarizer is 1,4-benzoquinone, 2-phenyl-1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2-tert-butyl-1,4-benzoquinone, 2-methoxy-1,4-benzoquinone, 2,6-dimethyl-1,4-benzoquinone, 2,3-dimethyl-1,4-benzoquinone, trimethyl-1,4-benzoquinone, 2,6-dimethoxy-1,4-benzoquinone, 2,5-methoxy-1,4-benzoquinone, tetramethyl-1,4-benzoquinone, tetrafluoro-1,4-benzoquinone, 2,5-dichloro-1,4-benzoquinone, tetrachloro-1,4-benzoquinone, 2-chloro-1,4-benzoquinone, or a combination thereof.
4. The solid electrolytic capacitor of claim 1 , further comprising an anode termination that is in electrical contact with the anode body and a cathode termination that is in electrical connection with the solid electrolyte.
5. The solid electrolytic capacitor of claim 1 , further comprising a housing within which the capacitor element is enclosed.
6. The solid electrolytic capacitor of claim 5 , wherein the housing is formed from a resinous material that encapsulates the capacitor element.
7. The solid electrolytic capacitor of claim 1 , wherein the anode body includes tantalum.
8. The solid electrolytic capacitor of claim 1 , wherein the conductive polymer has repeating units of the following formula:
wherein,
R 7 is a linear or branched, C 1 to C 18 alkyl radical, C 5 to C 12 cycloalkyl radical, C 6 to C 14 aryl radical, C 7 to C 18 aralkyl radical, or a combination thereof; and
q is an integer from 0 to 8.
9. The solid electrolytic capacitor of claim 8 , wherein the conductive polymer is poly(3,4-ethylenedioxythiophene).
10. The solid electrolytic capacitor of claim 1 , wherein the conductive polymer is formed by in situ polymerization.
11. The solid electrolytic capacitor of claim 1 , wherein the conductive polymer is in the form of particles.
12. The solid electrolytic capacitor of claim 11 , wherein the solid electrolyte also contains a polymeric counterion.
13. The solid electrolytic capacitor of claim 1 , wherein the capacitor element further comprises a cathode coating that contains a metal particle layer that overlies the solid electrolyte, wherein the metal particle layer includes a plurality of conductive metal particles.
14. The solid electrolytic capacitor of claim 1 , wherein the capacitor exhibits an initial ESR at a temperature of about 23° C. and a high temperature ESR after being subjected to a temperature of about 125° C. for 1,000 hours, wherein the ratio of the high temperature ESR to the initial ESR is about 3.0 or less.
15. The solid electrolytic capacitor of claim 1 , wherein the capacitor exhibits an initial capacitance at a temperature of about 23° C. and a high temperature capacitance after being subjected to a temperature of about 125° C. for 1,000 hours, wherein the ratio of the high temperature capacitance to the initial capacitance is about 3.0 or less.
16. The solid electrolytic capacitor of claim 1 , wherein the capacitor exhibits an initial ESR at a temperature of about 23° C. and a high humidity ESR after being subjected to a relative humidity of about 85% and temperature of about 85° C. for 1,000 hours, wherein the ratio of the high humidity ESR to the initial ESR is about 2.0 or less.
17. The solid electrolytic capacitor of claim 1 , wherein the capacitor exhibits an initial capacitance at a temperature of about 23° C. and a high humidity capacitance after being subjected to a relative humidity of about 85% and temperature of about 85° C. for 1,000 hours, wherein the ratio of the high humidity capacitance to the initial capacitance is about 2.0 or less.
18. The solid electrolytic capacitor of claim 1 , wherein the depolarizer has a standard reduction potential of greater than 0.2.
19. The solid electrolytic capacitor of claim 1 , wherein the depolarizer constitutes from about 1 to about 500 parts per million of the solid electrolyte.