Objective 1

To learn the specific charge/discharge characteristics of a UltraCapacitor (SuperCapacitors) through experimental testing of a remote triggered Ultracapacitor Battery.

Objective 2 

Compare charge/ discharge caracteristics of Ultracapacitor battery with other batteries. Observe the quicker charge/ discharge behaviour and understand how to use them along side other batteries to handle surges

Objective 3

Study the graphs and understand how the charging/discharging is faster compared to other batteries in an Ultracapacitor. How a high value of voltage can get easily stored in an ultracapacitor and how quickly it allows discharging
Theory and Background

Ultracapacitors are energy storage devices in which the charges are stored electrostatically. They can withstand thousands of cycles than batteries.
This Ultracapacitor stores the charge without any chemical reaction which allows the Ultracapacitor to charge and discharge much faster than other batteries.

Construction and Operation

Ultracapacitors are made up of two metal plates coated with loosely packed activated carbon which is immersed in electrolyte with positive and negative ions .
When Voltage is applied, the positive ions from the electrolyte moves towards the negative electrode (Cathode) and the negative ions from the electrolyte moves towards the positive electrode(Anode). The separator prevents the charge in moving between the electrodes.

 

 

 

Measurement

     Capacitance

Capacitance is the ability of the capacitor to store electrical charge. Capacitance is measured in Farads(F).
Capacitance= (Magnitude of charge of the electrode (Q))/(Magnitude of voltage of the electrode (V))

     Voltage

By Ohm’s law, Voltage of the capacitor is the product of current and resistance of the conductor or the potential difference across the terminals of the ultacapacitor.
Voltage= Current*Resistance

      Power

Power of the capacitor is the product of the measured Voltage and Current
Power= Voltage* Current

      Energy

Energy stored (E) of the Ultracapacitor is directly proportional to the capacitance.
E= 1/2CV2

UltraCapacitor

In 1957, General Electric engineers experimented on double layer capacitor. Standard oil rediscovered and patented it in 1966. After 1990’s first application was done in robots and  later in 2005, was used by aerospace company for door actuation and evacuation slides in airlines and jets. Later in 2007, advance in nanoscience developed advanced superionic conductors .

 

Ultracapacitor have a nominal single cell voltage of 2.3 to 2.75V, which is fixed by the battery chemistry. In order to obtain higher voltages, cells are put together in series. Ultracapacitor replaces Li-ion batteries in portable electronics.

 

The Specific Energy refers to the amount of energy that can be stored per unit weight. This value is very important for portable equipment as heavy batteries will be difficult and energy consuming to move around. The Specific Energy of Ultracapacitor is less than Li-ion batteries.

 

Energy Density describes how much energy can be stored per unit volume. Again, for portable electronic equipment, the space required for a given storage capacity is an important figure. The Energy Density for Ultracapacitor is comparable with Nickel Metal Hydride and is higher than Ni-Cad and lead-acid batteries.

 

Specific Power refers to the maximum amount of power can that can be delivered. In electrical terms, this is the maximum discharge Rate of the battery. Performance is much greater compared to other rechargeable batteries.

 

Farad is the unit of capacitance named after the physicist Michael Faraday. Ultracapacitor increased its capacitance to few thousand farads after a series of research to increase capacitance. The maximum voltage as of 2011 is 5V and the life cycle of ultracapacitor is huge can be cycled more than a million or 30,000h.

      Advantages

Ultracapacitor have high specific power and low resistance which supports high load currents. It has unlimited life cycle which be charged and discharged to maximum in few seconds.

      Disadvantages

High cost with low specific energy and high self discharge than other rechargeable batteries. Many Ultracapacitor has to be connected in series to prevent voltage balancing as it has low cell voltage.

      Applications

Used mobile phones, laptop computers, heavy duty vehicles, motor racing, UPS and in aircrafts.

Ultracapacitor Functions

Secure power

Provides reliable interim power, even if the primary source fails or fluctuates

Energy storage

Stores energy from low power sources, enabling support for high power loads

Pulse power

Supplies peak power to the load while drawing average power from the source

User Benefits

• Reduces the size & weight of the battery / power source required
• Improves run-time & battery life, particularly at cold temperatures
• Enables more power-hungry features, being used more often
• Can remove the need for a battery & harvest energy from clean sources
• Protects against accidental power loss or fluctuations/interruptions
• Doesn’t need to be replaced like batteries (unlimited discharge cycles)
• Environmentally friendly & safe

Difference between power and energy​ densities for an ultra capacitor compared to a battery is given in the below graph: