Supercapacitor Operation and Features Supercapacitor is a capacitor with a large capacitance. The capacitance of a capacitor depends on the distance between the electrodes and the surface area of the electrode. In order to obtain a larger capacitance, the supercapacitor minimizes the distance between electrodes and increases the surface area of the electrode.
When the potential between the two plates is lower than the redox potential of the electrolyte, the charge on the interface of the electrolyte will not deviate from the electrolyte, and the supercapacitor is in normal working condition; if the voltage across the capacitor exceeds the redox potential of the electrolyte, the electrolysis The liquid will decompose and become abnormal. As the super capacitor discharges, the charge on the positive and negative plates is discharged by the external circuit, and the charge response at the electrolyte interface decreases. Unlike batteries that use chemical reactions, the charging and discharging process of a supercapacitor is a physical process with no chemical reaction. The materials used are safe and non-toxic.
Supercapacitors can be quickly charged in dozens of seconds to minutes, with a long charge and discharge life of up to 500,000, or 90,000 hours; they can provide high discharge currents, such as the 2700F supercapacitor rated discharge current is not less than 950A, discharge peak current up to 1680A. The battery usually cannot have such a high discharge current, otherwise the life will be greatly shortened.
Supercapacitors can operate normally over a wide temperature range (-40°C to +70°C); they can be used in parallel to increase the capacity. If voltage equalization measures are taken, they can also be used in series.
Super capacitor selection Many users have encountered the same problem, that is how to calculate the discharge capacity of a certain capacity of a super capacitor when discharging with a certain current, or according to the discharge current and discharge time, how to choose the capacity of the super capacitor, we give below A simple computing company, based on this formula, can simply calculate the capacitance, discharge current, and discharge time, which is very convenient.
The two main applications of supercapacitors are: high power pulse applications and instantaneous power retention. The characteristics of high-power pulse applications are: instantaneous flow into the load with high current; characteristics of the instantaneous power retention application: the requirement to continuously provide power to the load, the duration is generally a few seconds or minutes. A typical application of instantaneous power retention: the disk drive head is reset when the power is turned off. Different applications have different parameter requirements for ultracapacitors. The high-power pulse application utilizes a small internal resistance (R) of the ultracapacitor, while the instantaneous power maintenance utilizes a large capacitance (C) of the ultracapacitor.
Instantaneous power maintains an approximate formula for the application of the capacitance of the supercapacitor, which is based on the principle of maintaining the required energy = supercapacitor to reduce energy.
Energy required during maintenance = 1/2I(Uwork+Umin)t;
Ultracapacitor energy reduction = 1/2C (Uwork2-Umin2),
Thus, its capacity can be obtained (ignoring the pressure drop caused by IR) C=(Uwork+Umin)t/(Uwork2-Umin2)
For example, in the SCM application system, the super capacitor is used as a backup power source. After the power is turned off, the super capacitor is required to maintain the current of 100 mA. The duration is 10 s. The SCM system cuts off the working voltage to 4.2 V. How much capacitance is needed to guarantee the system? normal work?
From the above formula, we can see:
Work start voltage Vwork=5V; Work cut-off voltage Vmin=4.2V; Working time t=10s; The required capacitance of the working power I=0.1A is:
C=(Vwork+Vmin)It/(Vwork2-Vmin2)
=(5+4.2)*0.1*10/(52-4.22)
=1.25F
According to the calculation results, a 5.5V 1.5F capacitor can be selected to meet the requirement.
High-power characteristics of the super capacitor Application 1, low temperature start in the winter in northern China, due to low temperatures, heavy batteries, tanks, armored vehicles and other vehicles that use the battery as starting power are often difficult to start. In a low-temperature environment, the discharge capacity decreases significantly, and the internal resistance increases drastically, which leads to low-temperature large-current discharge performance and output power of the battery. This may cause the vehicle to be difficult to start (for a long time) or even fail to start, affecting normal work and military readiness. The supercapacitor has the characteristics of normal operation in the temperature range of -40 to +70°C, which can provide an excellent solution for low-temperature start-up and can protect the battery and prolong the service life of the battery.
Case: A type of infantry fighting vehicle of our army and the Russian Army's tank and armored vehicle started to use the super capacitor emergency starting power supply system in cold weather to realize the emergency start of the tank under negative temperature and negative temperature.
2. Aircraft Startup Currently, the main problem with the power car for starting military aircraft (including helicopters) is that the generator output power cannot meet the requirements under certain shock or surge conditions, causing the engine speed and output power to drop rapidly or even turn off. For battery starter vehicles, supercapacitor modules can be connected in parallel with the batteries to provide the high currents needed for the aircraft engine start-up moments, improve start-up performance and wartime portable maneuverability, shorten the start-up time, and reduce the damage caused by the instantaneous high current to the battery. .
Case: During the 5.12 Wenchuan Earthquake rescue and disaster relief, the use of super-capacitors as a starting power source for helicopters played a key role and was well received by the military.
3. Application in near-defense weapons The carrier-based and land-based short-range high-speed anti-aircraft artillery systems use an external power supply system and require energy storage devices such as batteries to form an energy storage system, but the artillery requires instantaneous high-power in the firing process. Energy support, the battery power performance is poor, frequent high-power discharge is bound to drastically reduce its life expectancy, while the battery also needs to be regularly maintained, low temperature performance and a series of problems. The supercapacitor has nearly ten times higher pulse power than the battery, can achieve frequent high-power discharge, maintenance-free, high and low temperature performance, and the specific capacity is more than a hundred times higher than the ordinary capacitor and many other advantages, so that it can be used as an alternative battery performance is excellent Energy storage device.
4. Applications in vehicle acceleration, hill climbing, etc. The vehicle battery must have a certain capacity to meet the design needs of the vehicle, and must also have a certain peak power characteristics to meet the special conditions of acceleration and climbing. demand. The high power load condition caused by sudden acceleration, braking or climbing, and heavy load conditions during the driving of the vehicle requires the battery to realize high power discharge, and the high power performance of the battery is insufficient, even if high power discharge can be realized. Its life span has an impact. If supercapacitors are used in parallel with the batteries, the supercapacitor's high power advantage can be used to effectively compensate for the lack of battery power.
Supercapacitor Operation and Features Supercapacitor is a capacitor with a large capacitance. The capacitance of a capacitor depends on the distance between the electrodes and the surface area of the electrode. In order to obtain a larger capacitance, the supercapacitor minimizes the distance between electrodes and increases the surface area of the electrode. 
