Aluminum polymer capacitor with enhanced internal conductance and breakdown voltage capability
An improved capacitor is provided. The capacitor comprises a working element wherein the working element comprises an anode comprising a first dielectric on the anode, a cathode and a conductive separator between the first dielectric and cathode. The conductive separator comprises a separator and a first conductive polymer wherein the first conductive polymer at least partially encapsulates the separator. A second conductive polymer at least partially encapsulates the first conductive polymer and wherein the first conductive polymer has a higher conductivity than the second conductive polymer. An anode lead is in electrical contact with the anode and a cathode lead is in electrical contact with the cathode.
1. A method for forming a capacitor comprising:
forming a working element by:
providing an anode comprising a first dielectric and an anode lead;
providing a cathode comprising a cathode lead;
forming a conductive separator comprising a separator and a first conductive polymer wherein said first conductive polymer at least partially encapsulates said separator;
winding said anode and said cathode with said conductive separator between said first dielectric and said cathode to form a wound capacitor precursor; and
introducing a second conductive polymer into said wound capacitor precursor wherein said second conductive polymer at least partially encapsulates said first conductive polymer.
2. The method for forming a capacitor of claim 1 wherein said first conductive polymer is formed by in situ polymerization techniques.
3. The method for forming a capacitor of claim 1 wherein said introducing slurry into said wound capacitor precursor wherein said slurry comprises a pre-formed conductive polymer.
4. The method for forming a capacitor of claim 1 wherein said first conductive polymer has a higher conductivity than said second conductive polymer.
5. The method for forming a capacitor of claim 4 wherein said first conductive polymer has a first conductivity and said second conductive polymer has a second conductivity wherein said first conductivity is at least 150% to no more than 2500% of said second conductivity.
6. The method for forming a capacitor of claim 1 wherein said first conductive polymer has a first breakdown voltage and said second conductive polymer has a second breakdown voltage wherein said second breakdown voltage is higher than said first breakdown voltage.
7. The method for forming a capacitor of claim 6 wherein said second breakdown voltage is 120% to 700% of said first breakdown voltage.
8. The method for forming a capacitor of claim 1 wherein said first conductive polymer has a first work function and said second conductive polymer has a second work function wherein said second work function is higher than said first work function.
9. The method for forming a capacitor of claim 8 wherein said second work function is at least 0.2 eV to no more than 1.2 eV higher than said first work function.
10. The method for forming a capacitor of claim 1 further comprising:
adding a liquid electrolyte to said working element wherein said liquid electrolyte is between said dielectric and said cathode.
11. The method for forming a capacitor of claim 1 wherein said conductive separator has a first conductive polymer coating weight of at least 0.1 mg/cm 2 to no more than 10 mg/cm2.
12. The method for forming a capacitor of claim 1 wherein said conductive separator comprises a separator with said first conductive polymer coated on said material or said first conductive polymer impregnates said separator.
13. The method for forming a capacitor of claim 12 wherein at least one of said first conductive polymer or said second conductive polymer comprises a polymer selected from the group consisting of polyaniline, polythiophene and polypyrrole.
14. The method for forming a capacitor of claim 13 wherein said polythiopene is poly 3,4-ethylenedioxythiophene.
15. The method for forming a capacitor of claim 13 wherein said first conductive polymer or said second conductive polymer is a self-doping polymer.
16. The method for forming a capacitor of claim 1 comprising forming multiple anode leads or multiple cathode leads.
17. The method for forming a capacitor of claim 1 wherein at least one of said anode or said cathode comprises a valve metal.
18. The method for forming a capacitor of claim 17 wherein said valve metal is selected from the group consisting of tantalum, aluminum, niobium, titanium, zirconium, hafnium, alloys of these elements and a conductive oxide thereof.
19. The method for forming a capacitor of claim 18 wherein said valve metal is aluminum.
20. The method for forming a capacitor of claim 1 having a rated voltage of at least 15 volts to no more than 500 volts.
21. The method for forming a capacitor of claim 1 wherein said first conductive polymer has an average particle size which is higher than an average particle size of said second conductive polymer.
22. The method for forming a capacitor of claim 21 wherein said second conductive polymer is a soluble conductive polymer.
23. The method for forming a capacitor of claim 21 wherein said second conductive polymer has a particle size of no more than 200 nm.
24. The method for forming a capacitor of claim 21 wherein said particle size is at least 1 nm.
25. The method for forming a capacitor of claim 24 wherein said particle size is at least 20 nm.