Solid electrolytic capacitor containing a pre-coat and intrinsically conductive polymer
A solid electrolytic capacitor containing a capacitor element is provided. The capacitor element contains an anode body, a dielectric that overlies the anode body, a pre-coat that overlies the dielectric and that is formed from an organometallic compound, and a solid electrolyte that overlies the dielectric. The solid electrolyte includes an intrinsically conductive polymer containing repeating thiophene units of a certain formula.
1. A solid electrolytic capacitor comprising a capacitor element, wherein the capacitor element comprises:
an anode body;
a dielectric that overlies the anode body;
a pre-coat that overlies the anode body, wherein the pre-coat is formed from a monoaminofunctional silane that is a primary amine;
a solid electrolyte that includes:
at least one inner layer that overlies the pre-coat, is generally free of extrinsically conductive polymers, and contains an intrinsically conductive polymer containing repeating thiophene units of the following general formula (I):
wherein,
a is from 0 to 10;
b is from 1 to 18;
R is an optionally substituted C 1 -C 6 linear or branched alkyl group or a halogen atom; and
M is a hydrogen atom, an alkali metal, NH(R 1 ) 3 , or HNC 5 H 5 , wherein R 1 is each independently a hydrogen atom or an optionally substituted C 1 -C 6 alkyl group; and
at least one outer layer that overlies the inner layer, wherein the outer layer includes conductive polymer particles containing a complex of an extrinsically conductive thiophene polymer and a counterion; and
an external polymer coating that overlies the solid electrolyte and includes conductive polymer particles containing a complex of an extrinsically conductive thiophene polymer and a counterion;
wherein the capacitor exhibits a charge-discharge capacitance after being subjected to 5,000 cycles of a surge voltage and an initial capacitance prior to being subjected to the 5,000 cycles of the surge voltage, wherein the ratio of the charge-discharge capacitance to the initial capacitance is from about 0.9 to 1.
2. The solid electrolytic capacitor of claim 1 , wherein a is 1 and b is 3 or 4.
3. The solid electrolytic capacitor of claim 1 , wherein R is methyl.
4. The solid electrolytic capacitor of claim 1 , wherein M is an alkali metal.
5. The solid electrolytic capacitor of claim 1 , wherein the thiophene repeating units are formed from sodium 3-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-ethyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propyl-1-propane-sulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-pentyl-1-propane-sulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopropyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isobutyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopentyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-fluoro-1-propanesulfonate, potassium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid, ammonium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propane-sulfonate, triethylammonium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, or a combination thereof.
6. The solid electrolytic capacitor of claim 1 , wherein the polymer has a specific conductivity of about 20 S/cm or more.
7. The solid electrolytic capacitor of claim 1 , wherein the outer layer contains a hydroxyl-functional nonionic polymer.
8. The solid electrolytic capacitor of claim 1 , wherein the primary amine is 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, m-aminophenyltrimethoxysilane, p-aminophenyltrimethoxysilane, aminophenyltrimethoxysilane, 3-aminopropyltris(methoxy-ethoxy)silane, 11-aminoundecyltriethoxysilane, 2(4-pyridylethyl)triethoxysilane, 2-(trimethoxysilylethyl)pyridine, N-(3-trimethoxysilylpropyl)pyrrole, 3-(m-aminophenoxypropyltrimethoxysilane, aminopropylsilanetriol, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropyldimethylethoxysilane, or a combination thereof.
9. The solid electrolytic capacitor of claim 1 , wherein the external polymer coating further comprises a crosslinking agent.
10. The solid electrolytic capacitor of claim 1 , wherein the anode body is a sintered pellet.
11. The solid electrolytic capacitor of claim 1 , wherein the anode body is a foil.
12. The solid electrolytic capacitor of claim 1 , further comprising a housing within which the capacitor element is enclosed.
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 a breakdown voltage of about 55 volts or more.