The modern super capacitor is not a battery but crosses the boundary into battery technology by using special electrodes , the double layer capacitor concept and electrolyte .organic electrolyte that is easy to manufacture and is the most common system in use today.all capacitors have voltage limits while the electrostatic capacitor can be made to withstand high voltages super capacitors is confined to 2.5 to 2.7v. voltages of 2.8v and higher are possible but they would reduce the service life . To achieve higher voltages several super capacitors are connected in series .this has disadvantages serial connection reduce the total capacitance and strings of more than three capacitors require voltage balancing to prevent over voltage in any cell . This is similar to use the protection circuit in lithium ion batteries . The specific energy of the super capacitors is law and ranges from 1 to 30Wh/kg . Although high compared to a regular capacitor, Electrical energy can be stored directly by using super capacitors which are also known as ultra capacitors .super capacitors store electrical energy in the electric field between two electrodes applying dc voltage. The technology is enhanced by using modern materials which have higher dielectric constants thus providing much higher energy storage. While conventional capacitors have high power and low energy , super capacitors have high power as well as high energy.
The backup time is generally limited to not more than a few seconds. super capacitors have very fast charge and discharge rates. Super capacitors are safe because of the first discharge rate.the cycle life is virtually infinite and no maintenance is required . The super capacitors have a number of distinctive advantage over batteries.the super capacitors are further more environmental friendly, however the dc voltage requires a converter which negatively influence the efficiency and cost.the cost of super capacitors are high.