Carbon surface modification for three-volt ultracapacitor
An electric double-layer ultracapacitor configured to maintain desired operation at an operating voltage of three volts, where the capacitor includes a housing component, a first and a second current collector, a positive and a negative electrode electrically coupled to one of the first and second current collectors, and a separator positioned between the positive and the negative electrode. At least one of the positive electrode and the negative electrode can include a treated carbon material, where the treated carbon material includes a reduction in a number of hydrogen-containing functional groups, nitrogen-containing functional groups and/or oxygen-containing functional groups.
1. A method of making an ultracapacitor, comprising:
treating a carbon material to result in an about 10% to about 60% reduction in at least one functional group on a surface of the treated carbon material; and
forming a first electrode and a second electrode from the treated carbon material;
separating the first electrode and second electrode with a separator; and
inserting the first electrode and second electrode into a housing to form an ultracapacitor;
wherein the capacitor is configured to operate at 3 volts or greater at 65° C. and maintain greater than 80% of its initial capacitance for over 1500 hours.
2. The method of claim 1 , wherein the treated carbon material has about 20% to about 50% reduction in the number of the at least one functional group.
3. The method of claim 1 , wherein the at least one functional group is a hydrogen-containing functional group, a nitrogen-containing functional group, or an oxygen-containing functional group.
4. The method of claim 3 , wherein the treated carbon material comprises functional groups less than about 0.5% of which contains hydrogen.
5. The method of claim 3 , wherein the treated carbon material comprises functional groups less than about 0.1% of which contains nitrogen.
6. The method of claim 3 , wherein the treated carbon material comprises functional groups less than about 3% of which contains oxygen.
7. The method of claim 1 , wherein the capacitor is configured to operate at 65° C. with a cycle life of greater than 500 k cycles.
8. The method of claim 3 wherein the treated carbon material comprises about 30% fewer hydrogen-containing functional groups than an untreated carbon material.
9. The method of claim 1 , wherein the treated carbon material comprises functional groups less than about 1% of which contains hydrogen, less than 0.5% of which contains nitrogen, or less than about 5% of which contains oxygen.
10. The method of claim 1 , wherein the positive electrode comprises a first thickness and the negative electrode comprises a second thickness, wherein the first thickness of the positive electrode is greater than the second thickness of the negative electrode.
11. The method of claim 10 , wherein the first thickness is greater than the second thickness by 10%.
12. The method of claim 3 , wherein the treated carbon material comprises functional groups less than about 1% of which contains hydrogen.
13. The method of claim 3 , wherein the treated carbon material comprises functional groups less than about 0.5% of which contains nitrogen.
14. The method of claim 3 , wherein the treated carbon material comprises functional groups less than about 5% of which contains oxygen.
15. A method of making an ultracapacitor, comprising:
treating a carbon material to result in an about 10% to about 60% reduction in at least one functional group on a surface of the treated carbon material; and
forming a first electrode and a second electrode from the treated carbon material;
separating the first electrode and second electrode with a separator; and
inserting the first electrode and second electrode into a housing to form an ultracapacitor;
wherein the capacitor is configured to operate at 3 volts or greater at 65° C. and maintain less than 200% of its initial equivalent series resistance for over 1500 hours.
16. The method of claim 15 , wherein the capacitor is configured to operate at 3 volts or greater at 65° C. and maintain greater than 80% of its initial capacitance for over 1500 hours.
17. The method of claim 15 , wherein the treated carbon material has about 20% to about 50% reduction in the number of the at least one functional group.
18. The method of claim 15 , wherein the at least one functional group is a hydrogen-containing functional group, a nitrogen-containing functional group, or an oxygen-containing functional group.
19. The method of claim 18 , wherein the treated carbon material comprises functional groups less than about 0.5% of which contains hydrogen.
20. The method of claim 18 , wherein the treated carbon material comprises functional groups less than about 0.1% of which contains nitrogen.
21. The method of claim 18 , wherein the treated carbon material comprises functional groups less than about 3% of which contains oxygen.
22. The method of claim 15 , wherein the capacitor is configured to operate at 65° C. with a cycle life of greater than 500 k cycles.
23. The method of claim 18 , wherein the treated carbon material comprises about 30% fewer hydrogen-containing functional groups than an untreated carbon material.
24. The method of claim 15 , wherein the treated carbon material comprises functional groups less than about 1% of which contains hydrogen, less than 0.5% of which contains nitrogen, or less than about 5% of which contains oxygen.
25. The method of claim 15 , wherein the positive electrode comprises a first thickness and the negative electrode comprises a second thickness, wherein the first thickness of the positive electrode is greater than the second thickness of the negative electrode.
26. The method of claim 25 , wherein the first thickness is greater than the second thickness by 10%.
27. A method of making an ultracapacitor, comprising:
treating a carbon material to form a treated carbon material;
forming a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode comprises the treated carbon material;
separating the first electrode and second electrode with a separator; and
inserting the first electrode and second electrode into a housing to form an ultracapacitor;
wherein the treated carbon material has at least one functional group on a surface of the treated carbon material less than about 1% of which contains hydrogen, less than 0.5% of which contains nitrogen, or less than about 5% of which contains oxygen;
wherein the ultracapacitor is capable of operating at 3 volts at a temperature of 65° C. or greater while maintaining less than 200% of its initial equivalent series resistance for over 1500 hours.