Solid electrolytic capacitor with an ultrahigh capacitance

1. A solid electrolytic capacitor comprising:

an anode that contains a dielectric formed on a sintered porous body, wherein the sintered porous body is formed from a valve metal powder having a specific charge of about 100,000 microFarads*Volts per gram or more; and

a solid electrolyte overlying the anode, wherein the solid electrolyte includes an intrinsically conductive polymer containing repeating units having the following formula (I):

wherein, R is (CH2)a-O—(CH2)b;

a is from 0 to 10;

b is from 1 to 18;

Z is SO 3 ; and

X is an alkali metal;

wherein the solid electrolyte is formed from multiple layers, at least one of which contains the intrinsically conductive polymer;

wherein the solid electrolyte contains an inner layer and an outer layer, the inner layer containing the intrinsically conductive polymer;

wherein the inner layer is free of extrinsically conductive polymers.

2. The solid electrolytic capacitor of claim 1 , wherein the powder contains primary particles having a median size of from about 5 to about 500 nanometers.

3. The solid electrolytic capacitor of claim 1 , wherein the powder includes tantalum.

4. The solid electrolytic capacitor of claim 1 , wherein a is 1 and b is 3 or 4.

5. The solid electrolytic capacitor of claim 1 , wherein the polymer is a homopolymer.

6. The solid electrolytic capacitor of claim 5 , wherein the homopolymer is poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butane-sulphonic acid, salt), poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-propanesulphonic acid, salt), or a combination thereof.

7. The solid electrolytic capacitor of claim 1 , wherein the solid electrolyte further includes an extrinsically conductive polymer having repeating units of the following formula (III):

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 C 1 to C 4 hydroxyalkyl radical, or hydroxyl radical; and

q is an integer from 0 to 8.

8. The solid electrolytic capacitor of claim 7 , wherein the extrinsically conductive polymer is poly(3,4-ethylenedioxthiophene).

9. The solid electrolytic capacitor of claim 1 , wherein each of the layers contains the intrinsically conductive polymer.

10. The solid electrolytic capacitor of claim 1 , wherein the outer layer contains an extrinsically conductive polymer.

11. The solid electrolytic capacitor of claim 10 , wherein the extrinsically conductive polymer is poly(3,4-ethylenedioxthiophene).

12. The solid electrolytic capacitor of claim 11 , wherein the outer layer further comprises a polymeric counter anion.

13. The solid electrolytic capacitor of claim 1 , further comprising an external polymer coating that overlies the solid electrolyte, wherein the external polymer coating contains conductive polymer particles.

14. The solid electrolytic capacitor of claim 1 , further comprising an anode termination that is electrically connected to the anode and a cathode termination that is electrically connected to the solid electrolyte.

15. The solid electrolytic capacitor of claim 1 , wherein the capacitor exhibits a wet-to-dry capacitance of about 50% or more.

16. A solid electrolytic capacitor comprising:

an anode that contains a dielectric formed on a sintered porous body, wherein the sintered porous body is formed from a valve metal powder having a specific charge of about 100,000 microFarads*Volts per gram or more; and

a solid electrolyte overlying the anode, wherein the solid electrolyte includes an intrinsically conductive polymer containing repeating units having the following formula (I):

wherein, R is (CH2)a-O—(CH2)b;

a is from 0 to 10;

b is from 1 to 18;

Z is SO 3 ; and

X is an alkali metal;

wherein the solid electrolyte is free of extrinsically conductive polymers.

17. The solid electrolytic capacitor of claim 16 , further comprising an external polymer coating that overlies the solid electrolyte, wherein the external polymer coating contains conductive polymer particles.

18. A method for forming a solid electrolytic capacitor, the method comprising:

pressing a powder into the form of a pellet, wherein the powder has a specific charge of about 100,000 pF*V/g or more;

sintering the pellet;

anodically oxidizing the sintered pellet to form a dielectric layer that overlies the anode; and

dipping the anodically oxidized pellet into a solution that contains an intrinsically conductive polymer containing repeating units having the following formula (I):

wherein, R is (CH2)a-O—(CH2)b;

a is from 0 to 10;

b is from 1 to 18;

Z is SO 3 ; and

X is an alkali metal;

wherein the solid electrolyte is formed from multiple layers, at least one of which contains the intrinsically conductive polymer;

wherein the solid electrolyte contains an inner layer and an outer layer, the inner layer containing the intrinsically conductive polymer;

wherein the inner layer is free of extrinsically conductive polymers.

19. The method of claim 18 , wherein the polymer is poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butane-sulphonic acid, salt), poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-propanesulphonic acid, salt), or a combination thereof.

20. The method of claim 18 , further comprising applying a dispersion to the anodically oxidized pellet after dipping into the solution, wherein the dispersion contains extrinsically conductive polymer particles.

21. The method of claim 20 , wherein particles contain poly(3,4-ethylenedioxthiophene) and polystyrene sulfonic acid.