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Supercapacitors:

Supercapacitors:. Decreasing Resistance Through Tape Casting. Submitted to Dr. Yury Gogotsi, John Chmiola, and the Drexel University Engineering Faculty. Dan Berrigan – DREAM Fellow. Overview. Motivation - Impending Oil Crisis - Uses in Hybrid Vehicles Introduction - Supercapacitors

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Supercapacitors:

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  1. Supercapacitors: Decreasing Resistance Through Tape Casting Submitted to Dr. Yury Gogotsi, John Chmiola, and the Drexel University Engineering Faculty Dan Berrigan – DREAM Fellow

  2. Overview Motivation - Impending Oil Crisis - Uses in Hybrid Vehicles Introduction - Supercapacitors - Making the electrode - Problems with current method Goals Tape Casting - Problems encountered - Overall solution Future Work

  3. Motivation • Impending Oil Crisis • Rising costs of Crude Oil • 70% of oil goes to transportation • China becoming increasingly modernized • Hybrid Electric Vehicles • Batteries supply bursts of power to a gasoline engine • Temporary solution to slow oil consumption Cars like Honda’s Civic Hybrid, if widely accepted can reduce the dependence on foreign oil. Problems with Batteries www.honda.com • Low power density and add weight • Increase the cost of the car • Lose 20% of the energy put into them Thermoanalytics. (2001). Battery Types and Characteristics. 2004.

  4. The Super Solution • Works by charge separation of an electrolytic solution with a non-interacting electrode • Cheaper and easier to produce • Higher power density • Completely reversible reaction • Higher capacitance than traditional capacitors Pores in the Carbide Derived Carbon allow ions of sulfuric acid to gather inside the electrode when a voltage is applied to the supercapacitor. Chmiola, John. “Supercapacitance Measurements of Porous Carbon Obtained Through Chlorination of Metal Carbides.” Senior Design Drexel U., 2004.

  5. Building the Supercapacitor Schematic showing the components of a test cell Chmiola, John. “Supercapacitance Measurements of Porous Carbon Obtained Through Chlorination of Metal Carbides.” Senior Design Drexel U., 2004.

  6. Making the Electrode  Several problems were inherent to this process: the mix of binder and carbon was not homogeneous, the electrode is not in complete contact with current collector, and it is patented already. Chmiola, John. “Supercapacitance Measurements of Porous Carbon Obtained Through Chlorination of Metal Carbides.” Senior Design Drexel U., 2004.

  7. Goals 200 180 160 140 120 Capacitance (F/g) 100 80 60 40 20 0 a-C [3] SWNT [2] C cloth [4] MWNT [1] B4C@1000C fb-MWNT [3] Ti2AlC@1000C Previous work found that Ti2AlC had a higher specific capacitance than carbon nanotubes. However, the high resistances makes the power much less. • Invent a process that decreases the resistance between the current collector and the electrode • Decrease the resistance inside the carbon electrode

  8. Tape Casting → A slurry of carbon, NMP solvent, and PVDF binder is made. The slurry is deposited on electrodes and a doctor’s blade is passed over it. → The electrodes are heated in an oven to evaporate the solvent.

  9. Tape Casting Process Creating the Slurry • 1) Use mortar and pestle to grind the carbon grains for 10 minutes. • Weigh the carbon and 5 wt% of polyvinylidene fluoride (PVDF) in separate containers. • Mix in with a pipette solvent, N-Methyl-2-Pyrrolidone (NMP) — enough to the carbon to make it into a thick paste. In the other container, add enough solvent to completely dissolve the PVDF. • Sonicate both for 10 minutes. • Add the PVDF and solvent to the carbon and mix for 15 minutes. If the slurry has a low viscosity, then heat it at a temperature between 80-100 °C during mixing.

  10. Problems Encountered • Must have viscosity of maple syrup • Must be free of lumps • Must be cast directly onto electrodes Solved by careful moderation of solvent. Solved by mixing carbon with solvent and binder with solvent separately, then sonicating for 10 minutes. • Solved by drilling holes into a wooden board.

  11. Tape Casting Process Casting the Electrode • Wrap electrode edge in masking tape. • Slide it into a hole in the wooden board. • Deposit a small amount of slip (2-3 drops) using a pipette. 4) Pass doctors blade over electrode. 5) Bake in ~100°C oven for 20 minutes.

  12. Future Work • Carbon nanotubes • Metal powder (Cr, Al) • Different binder (Teflon, PVDC) • Electrochemical Analysis of the Samples • Improve Final Tape Properties

  13. Acknowledgements John Chmiola Dr. Yury Gogotsi Dorilona Rose DREAM Program Drexel University

  14. References Chmiola, John. “Supercapacitance Measurements of Porous Carbon Obtained Through Chlorination of Metal Carbides.” Senior Design Drexel U., 2004. Singer, Clifford. “Energy Usage.” http://acdisweb.acdis.uiuc.edu/NPRE201/fall02web/lectures_pdf/lecture03.pdf. 4 Sept. 2003. Thermoanalytics. (2001). Battery Types and Characteristics. 2004.

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