ACTE UK > Technologies > Ultracapacitors

 

Ultracapacitors

 

Ultracapacitors are essentially large supercapacitors, positioned between conventional electrolytic capacitors and rechargeable batteries. They can support (or potentially replace) batteries and other energy sources in many applications.
 
The high power, high energy and long-term reliability of LS Ultracapacitors enables use in many more industrial applications where current-limited or fluctuating power generation and supply would otherwise require complex or non financially-viable designs. These include backup power and auxiliary power units, instantaneous & peak power compensation and energy storage as well.
 

Ultracapacitor cell. (Click to enlarge)

Charging process (click to enlarge)

Ultracapacitor cell characteristics
  • Rated Voltage: up to 2.8 V
  • High Power Performance (vs. Battery)
  • High Energy Performance (vs. Capacitor)
  • Environment-friendly
  • Maintenance-free
  • Wide operating temperature range:                    -40°C ~ 65°C
  • Low internal resistance
  • Balancing and Over voltage: Protection of Individual Cell
  • Easy build-up design for High voltage module
  • Efficient Heat transfer to outside
Higher voltage multi-cell module information

Ultracapacitor Comparisons

Many people like to make comparisons between ultracapacitors and rechargable cells. Below are some facts:

Parameters Electrostatic
Capacitor
Ultracapacitor
Rechargeable
Battery
Discharge rate 10-6 ~ 10-3 sec 1 ~ 30 sec 0.3 ~ 4 hrs
Charge rate 10-6 ~ 10-3 sec sec ~ min 0.5 ~ 5 hrs
Energy Density (Wh/kg) <0.1 1 ~ 10c 30 ~ 100
Power Density (W/kg) >10,000 1,000 ~ 2,000 50 ~ 200
Charge/Discharge
Efficiency
~ 1.0 0.9 ~ 0.95 0.7 ~ 0.85
Cycle life infinite >500,000 500 ~ 2,000
 
Different units of measurement between ultracapacitors (Farads) and batteries (Ampere-hours or Watt -hours) increase confusion when adopting ultracapacitors into systems.
 

The amount of energy stored in an ultracapacitor can be easily calculated by using following equation:

Energy (Joule) = ½ x Capacitance (Farad) x Voltage2 (Volts)
 

This can be converted from Farad for Ultracapacitors to Watt-hour unit for conventional batteries by:

Energy (Watt hour) = Energy (Joule) / 3600 (seconds)

LS Mtron recommended to operate ultracapacitors from maximum voltage to half voltage and which utilises ¾ of total stored energy.

Another important distinction between ultracapacitors and batteries is the way the nominal voltage varies during the charge-discharge process which can influence selection and type of external circuitry.

   Capacity of Cell   
    Ultracapacitor    
Units [F]
Conversion to
Battery Units [Wh]

 

Operation voltage
(2.8V - 1.4V)

120 F 98 mWh
350 F 286 mWh
3000 F 2.45 Wh
 Comparison of relative energy
 
 

 

Ultracapacitor Technology

The high content of energy stored by ultracapacitors in comparison to conventional electrolytic capacitor is due to the activated carbon electrode material having extremely high surface area. Additionally there is a very short distance of charge separation in the interface between electrode and electrolyte.

The ultracapacitors high power, long shelf and cycle life performance are due to the energy storage principal differing from batteries. In a battery, energy is stored and released via chemical reaction inside, but this caused electrode material degradation which affects the overall system.

Ultracapacitors use a physical charge separation phenomena between electrode and ions in electrolyte at the interface. Since charge and discharge process are purely physical and highly reversible, Ultracapacitors can release energy much faster (with more power) than a battery that relies on slow chemical reactions and can also be cycled hundreds of thousands of times without deep effect on performance.

Ultracapacitor Cell Construction

 

 

 

Ultracapacitors.jpgFull product details of our range of ultracapacitors can be found on the

Ultracapacitor Products Page