Linear-hyperbranched polymers as performance additives for solid electrolytic capacitors
Provided herein is an improved capacitor and a method for forming an improved capacitor. The method includes providing an anode and forming a dielectric on the anode. A linear-hyperbranched polymer is formed and a conductive polymer dispersion is prepared comprising at least one conducting polymer, one polyanion and the linear-hyperbranched polymer. A layer of the conductive polymer dispersion if formed wherein said dielectric is between the anode and the layer.
1. A capacitor comprising:
an anode;
a cathode wherein said cathode comprises a linear-hyperbranched polymer
wherein said linear-hyperbranched polymer comprises a linear portion and a hyperbranched portion wherein said linear portion comprises at least two reactive end groups selected from the group consisting of hydroxyl, amino and epoxy; and
a dielectric between said anode and said cathode.
2. A capacitor comprising:
an anode;
a cathode wherein said cathode comprises a linear-hyperbranched polymer
wherein said linear-hyperbranched polymer comprises a linear portion and a hyperbranched portion wherein said linear portion comprises at least one of polyamide-ester-amide, polyesteramide and polyesteramine; and
a dielectric between said anode and said cathode.
3. A capacitor comprising:
an anode;
a cathode wherein said cathode comprises a linear-hyperbranched polymer wherein said linear-hyperbranched polymer comprises a hyperbranched portion and a linear portion wherein said linear portion comprises:
wherein R 21 and R 25 are terminating groups;
R 22 , R 23 and R 24 are independently alkyls or substituted alkyl of 1 to 50 carbons;
n is an integer; and
wherein R 21 , R 22 , R 23 , R 24 , R 25 and n are selected such that the molecular weight of said linear portion is no more than 1000; and
a dielectric between said anode and said cathode.
4. The capacitor of claim 3 wherein said anode comprises a valve metal or
a conductive compound of said valve metal.
5. The capacitor of claim 3 wherein said cathode comprises a conductive polymer or manganese dioxide.
6. The capacitor of claim 3 wherein said dielectric is an oxide of said anode.
7. The a capacitor of claim 3 wherein said linear-hyperbranched polymer is a reaction product of a diol and an anhydride to form a linear portion.
8. The capacitor of claim 7 wherein said diol is OH—R 1 —OH wherein R 1 is a linear alkyl.
9. The capacitor of claim 7 wherein said anhydride is defined by:
wherein R 2 is a linear alkyl of 1 to 6 carbons, which may be substituted, or the atoms necessary to form a ring which may be substituted.
10. The capacitor of claim 9 wherein said ring is an aromatic ring.
11. The capacitor of claim 7 further comprising reacting with an acrylate wherein said acrylate is defined by:
wherein R 3 is a linear alkyl of 1 to 50 carbons which may be substituted, an ether or polyether which may be substituted.
12. The capacitor of claim 11 wherein said acrylate is defined by:
wherein R7 is hydrogen or methyl and n is an integer of no more than 10.
13. The capacitor of claim 11 wherein said acrylate is selected from the group consisting of 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate (HEA), 2,2-bis(hydroxymethyl)propyl acrylate;
14. The capacitor of claim 7 wherein said linear-hyperbranched polymer is a second reaction product of a hydroxyl amine with said reaction product.
15. The capacitor of claim 14 wherein said hydroxyl amine is defined by
wherein R 5 and R 5′ are independently selected from linear alkyls of 1-6 carbons which may be substituted.
16. The capacitor of claim 15 wherein said hydroxyl amine is selected from:
17. The capacitor of claim 3 wherein said linear-hyperbranched polymer comprises at least Generation 1 branching.
18. The capacitor of claim 17 wherein said linear-hyperbranched polymer comprises at least Generation 2 branching.
19. The capacitor of claim 17 wherein said linear-hyperbranched polymer has an acid number of at least 100 to no more than 1000.
20. The capacitor of claim 19 wherein said linear-hyperbranched polymer has an acid number of no more than 200.
21. The capacitor of claim 3 wherein said cathode has a performance additive with no more than 10 wt % sulfonate.
22. The capacitor of claim 21 wherein said performance additive has no more than 0.1 wt % sulfonate.
23. The capacitor of claim 3 wherein said cathode has a performance additive with no more than 10 wt % primary or secondary amines.
24. The capacitor of claim 23 wherein said performance additive has no more than 10 wt % primary or secondary amines.
25. The capacitor of claim 3 further comprising a cross-linked cathode.
26. The capacitor of claim 25 wherein said cross-linked cathode is a reaction product of said cathode with a crosslinker.
27. The capacitor of claim 26 wherein said crosslinker is selected from a silane and a ethylene glycol diglycidyl ether.
28. The capacitor of claim 27 wherein said crosslinker is selected from the group consisting of: