Super Capacitors–The future of Batteries
Super–capacitors are unique electrical storage devices that can store much more energy than conventional capacitors, and offer higher power density than batteries. The combination of the super–capacitor connected in parallel to the battery gives the advantages of both, enhancing the performance of the battery and extending its life, exploiting the batteries to its maximum potential.
A pair of positive electric charges want nothing to do with each other. They move apart as fast as they can.
So if they are forced to move towards each other, they resist, and it takes energy to make this happen. The energy isn't used up and lost. It's stored, as an electric field–a kind of tension in space–for as long as the charges are held uncomfortably close together. When they become once again free to move, the charges use this energy to speed them on their way. A capacitor is a component specially designed to hold an electric field.
The energy stored in a capacitor is proportional to the capacitance. The energy stored in a capacitor is proportional to the square of the voltage across the capacitor.
Since the square of the voltage appears in the energy formula, the energy stored is always positive. There is no room for the negative amount of energy in the capacitor, that means whatever amount of energy enters into the capacitor, the same can be extracted. No extra amount of energy can be taken out than the amount it takes in.
Power in to the capacitor can be negative. Voltage can be positive while current is negative. Imagine a capacitor that is charged. We could charge a capacitor by putting a battery across the capacitor, for example. If we place a resistor across the capacitor, then the charge would leave the capacitor as the current would flow out of the capacitor along with the energy which becomes the heat energy in the resistor. As the energy leaves the capacitor, power turns out to be negative.