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Capacitors store electrical energy by accumulating charge on two parallel plates/ electrodes separated by a dielectric material. Aluminium Oxide is the dielectric material in the case of E caps. Capacitance value (C) of such a capacitor is given by the dielectric permittivity ꜫ, the distance d separating the electrodes, and the effective area A of the electrodes constituting the device, as per the following equation.
C = ꜪoꜪr A /d _{ }….equation 1
The energy stored in the device is given by the equation_{,}
E = ½ CV^{2 }….equation 2
Where E is the energy stored in the Capacitor, C is the capacitance value of the capacitor and V is the capacitor terminal voltage.
As can be seen from the equation, the amount of energy stored in the capacitor can be increased in two ways; one is to increase the terminal voltage and the other way is to increase the capacitance value of the capacitor. The value of terminal voltage is limited by the voltage withstand strength of the dielectric material between the electrodes.
The capacitance value of the device can be increased in three different ways,
1. by increasing the effective area of the electrodes,
2. by increasing the permittivity of the dielectric separating the electrodes and
3. by decreasing the distance between the two electrodes.
Another important factor about capacitor technology is the ESR, or Equivalent Series Resistance of the capacitor having a very important effect on the capacitor’s turnaround efficiency when charging and discharging of the capacitor.
Supercapacitors (SCs) / Ultracapacitors or Electrical Double Layer Capacitors (EDLC) is the latest addition to the Electrical Energy Storage Devices (EESDs) comprising Electrolytic Capacitors (E caps.) and Batteries.
Batteries are one of the most costeffective energy storage technologies available where the energy is stored electrochemically. All battery systems are made up of a set of low voltage/ power cells connected in series to achieve the desired terminal voltages and in parallel to provide the desired power ratings. Batteries can be charged and discharged in certain number of times given by the cycling capability of the electrode and the chemical used as electrode. Popular battery technologies are the Lithium – Ion and the Lead Acid Technologies. Batteries have fairly good energy density, power, life span and initial cost.
But they are of limited cycle life, higher maintenance cost, considerable weight and size. Also, there are some environmental concerns related to the use of batteries due to the hazardous material contained in them and the toxic gases generated during the charge – discharge cycles.
An ultracapacitor is constructed with symmetric carbon positive and negative electrodes separated by an insulating ionpermeable separator and packaged into a container filled with organic electrolyte (salt/solvent) designed to maximize ionic conductivity and electrode wetting. It is the combination of high surfacearea activated carbon electrodes with extremely small charge separation that results in high capacitance. An electrical double layer capacitor/Supercapacitor is nothing but a highcapacity capacitor with capacitance values much higher than normal capacitors but lower voltage limits. Supercapacitors store charge electrostatically (nonFaradaic) by reversible adsorption of the electrolyte onto electrochemically stable high surface area carbon electrodes. Charge separation occurs on polarization at the electrode/electrolyte interface, producing a double layer. They can store 10 to 100 times more energy per unit volume or mass than electrolytic capacitors, can receive and deliver charge much faster than batteries, and tolerate more chargingdischarging cycles than rechargeable batteries. The Supercapacitor offers excellent power handling characteristics when used by themselves or in combination with batteries provides extended backup time.
The energy stored in the device is given by the equation_{,}
E = ½ CV^{2 }….equation 2
Where E is the energy stored in the Capacitor, C is the capacitance value of the capacitor and V is the capacitor terminal voltage.
As can be seen from the equation, the amount of energy stored in the capacitor can be increased in two ways; one is to increase the terminal voltage and the other way is to increase the capacitance value of the capacitor. The value of terminal voltage is limited by the voltage withstand strength of the dielectric material between the electrodes.
The capacitance value of the device can be increased in three different ways,
1. by increasing the effective area of the electrodes,
2. by increasing the permittivity of the dielectric separating the electrodes and
3. by decreasing the distance between the two electrodes.
Another important factor about capacitor technology is the ESR, or Equivalent Series Resistance of the capacitor having a very important effect on the capacitor’s turnaround efficiency when charging and discharging of the capacitor.
Supercapacitors (SCs) / Ultracapacitors or Electrical Double Layer Capacitors (EDLC) is the latest addition to the Electrical Energy Storage Devices (EESDs) comprising Electrolytic Capacitors (E caps.) and Batteries.
Batteries are one of the most costeffective energy storage technologies available where the energy is stored electrochemically. All battery systems are made up of a set of low voltage/ power cells connected in series to achieve the desired terminal voltages and in parallel to provide the desired power ratings. Batteries can be charged and discharged in certain number of times given by the cycling capability of the electrode and the chemical used as electrode. Popular battery technologies are the Lithium – Ion and the Lead Acid Technologies. Batteries have fairly good energy density, power, life span and initial cost.
But they are of limited cycle life, higher maintenance cost, considerable weight and size. Also, there are some environmental concerns related to the use of batteries due to the hazardous material contained in them and the toxic gases generated during the charge – discharge cycles.
An ultracapacitor is constructed with symmetric carbon positive and negative electrodes separated by an insulating ionpermeable separator and packaged into a container filled with organic electrolyte (salt/solvent) designed to maximize ionic conductivity and electrode wetting. It is the combination of high surfacearea activated carbon electrodes with extremely small charge separation that results in high capacitance. An electrical double layer capacitor/Supercapacitor is nothing but a highcapacity capacitor with capacitance values much higher than normal capacitors but lower voltage limits. Supercapacitors store charge electrostatically (nonFaradaic) by reversible adsorption of the electrolyte onto electrochemically stable high surface area carbon electrodes. Charge separation occurs on polarization at the electrode/electrolyte interface, producing a double layer. They can store 10 to 100 times more energy per unit volume or mass than electrolytic capacitors, can receive and deliver charge much faster than batteries, and tolerate more chargingdischarging cycles than rechargeable batteries. The Supercapacitor offers excellent power handling characteristics when used by themselves or in combination with batteries provides extended backup time.
Equation of Capacitance, C = ε_{0}ε_{r }A/d, (C α A/d, where A – Surface Area, d thickness of dielectric)
In the case of Supercapacitors, due to the porous nature of Activated Carbon the surface area will be much higher, resulting in higher capacitance.
In the case of Supercapacitors, due to the porous nature of Activated Carbon the surface area will be much higher, resulting in higher capacitance.
Features
 The charging speed is fast, and it can reach more than 95% of its rated capacity by charging for milliseconds to few minutes.
 The cycle life is long, and the number of deep charge and discharge cycles can reach 10,000 to 500,000 times, without "memory effect";
 The high current discharge capacity is super strong, the energy conversion efficiency is high, the process loss is small, and the high current energy cycle efficiency is ≥90%;
 High power density, up to 300W/KG~5000W/KG, equivalent to 5~10 times of battery;
 The raw material composition, production, use, storage and dismantling process of the product are not polluted, and it is an ideal green environmental protection power source;
 The charging and discharging circuit is simple, no charging circuit like rechargeable battery is needed, and the safety factor is high, and the maintenance is longterm maintenancefree;
 Good ultralow temperature characteristics, temperature range 40 ° C ~ +70 ° C;
Comparison of Supercapacitor with Energy Storage Devices
Parameter  Supercapacitor  Ordinary Capacitor  Battery 

Energy storage  Wattsecond energy  Wattsecond energy  Watthour energy 
Power supply  Fast discharge, linear or exponential voltage decay  Fast discharge, linear or exponential voltage decay  Maintain a constant voltage for a long time 
Charging/discharging time  milliseconds to seconds  picoseconds to milliseconds  1 to 10 hours 
Dimensions  Small  Small to Large  Large 
Energy density  1 to 5Wh/kg  0.01 to 0.05Wh/kg  8 to 600Wh/kg 
Specific Power  210W/gm  >100W/gm  0.31.5W/gm 
Operating voltage  2.3V to 2.75V  6V to 800V  1.2V to 4.2V 
Life  ＞500,000 cycles  ＞100,000 cycles  150 to 1500 cycles 
Working temperature  ﹣40 to ﹢70℃  ﹣40 to ﹢125℃  ﹣20 to ﹢65℃ 