ULTRACAPACITORS

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ULTRACAPACITORS

• TO MEET AUTOMOTIVE POWER NEEDS

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Traditional capacitors

• Two electrodes, or plates separated by a
  dielectric
• Capacitors energy stored in electric field

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CONSTRUCTION

• Double-layer technology

• Electrodes Activated carbon (carbon cloth,
  carbon black, particulate from SiC )

• Electrolyte KOH, organic solutions, sulfuric
  acid

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Limitations of Activated Carbon

• Non uniform porosity
• Multiple time constant
• Much of the surface area is not utilized
• Limited ion mobility
• Limited conductivity due to amorphous nature of
  activated carbon
• Bonding limitation due to
• Electrode junction has high resistance
  
  

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Carbon Nanotube Enhanced Ultracapacitor
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Electrode structure of vetrically aligned carbon
nanotubes
Paintbrush structure
High tube density10 12 - 1013 CNT/cm Tube
spacing 5 -10 n Tube diameter 2 -5 n Tubes
length 120 -300 µm
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FEATURES

• Energy storage device with excellent power
  capabilities ,high reliability
• Long life -1 million charging cycles
• High capacitance about 3000F
• No chemical reaction
• Improved safety
• Enhance efficiency
• Optimize system size and cost

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Battery problems in hybridvehicles
Primary power system continuous
demand Secondary power system-- peak power demand

• Batteries have difficulty functioning
  in cold weather
• Limited life cycle results in replacements
• Limited in their ability to capture and provide
  bursts of high power
• Hence less efficient

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ADVANTAGES OVER BATTERIES

• Function well in cold weather, down to 40C,
  batteries do not operate well below 0C
• Long lifetime -1 million cycles , maintenance
  free
• more efficient than batteries( 84-95 ),
  batteries (70 )
• Environmentally friendly (No heavy metals)
• Up to ten times the power of batteries to boost
  the acceleration of a vehicle.

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Some comparisons
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OTHER APPLICATIONS

• Regenerative braking systems for hybrid vehicles
  and electric rail
• Battery free backup power systems
• Provide backup power for the memory used in
  microcomputers and cell phone
• Distributed power for vehicle systems
• Electric power grid
• Wind power and solar power

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• Air-conditioning
• Provide safety when a car has electrically
  actuated brakes or door locks and the wiring
  fails because of a defect or an accident
• Power lock

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THANK YOU

• QUESTIONS ?