super capacitors, also known as electrochemical capacitors, electric double layer capacitors, gold capacitor, farad capacitor is an electrochemical energy storage device by an electrolyte polarization from the 1970s and eighties developed.
1. super capacitor structure
Specific details on the structure of the supercapacitor depends on the application and use of supercapacitors. As manufacturers or specific application needs, these materials may vary slightly. All supercapacitor common is that they contain a positive electrode, a negative electrode, and a separator between the two electrodes, the electrolytes fill the two apertures separated by the two electrodes and the separator.
Structure of the supercapacitor. It is higher than the surface area of the porous electrode material, the current collector, a porous battery separator and electrolyte composition. Between the electrode material and the current collector to be closely linked, to reduce contact resistance; diaphragm conditions have as high ionic conductivity and electronic conductivity as low as possible should be met, electronic insulation materials usually fibrous structure, such as a polypropylene film . Type electrolytic solution is selected according to the nature of the electrode material.
2. Ultracapacitors classification and working principle
The basic principle of electric double layer capacitor and other types, are obtained using a large-capacity electric double layer structure of activated carbon and an electrolyte composed of a porous electrode. Highlighting the advantages of high power density, the charge and discharge time is short, long cycle life, wide operating temperature range, the maximum capacity is an electric double layer capacitor is in volume production in the world’s.
The energy storage mechanism can be divided into the following two categories:
1, electric double layer capacitor: in the electrode / solution interface of orientation caused by the charge of electrons or ions generated by the confrontation. One electrode / solution system, an electric double layer formed on the electrodes and the electron conducting ionically conductive electrolyte solution interface. When the electric field is applied across the two electrodes, the female solution, cationic respectively, an electric double layer formed on the surface of the positive electrode, negative electrode migration; undo the field, negative charges oppositely charged ions on the electrode with the solution phase the electric double layer suction stable, produce relatively stable potential difference between the positive and negative electrodes. For a time the electrode will produce anisotropic ionic charge and the charge on the electrodes of the same amount within a certain distance (dispersion layer), so as to maintain electrical neutrality; poles when communicating with the external circuit, the electrode charge migration current is generated in the external circuit, the ions in solution migrate into electrically neutral solution, which is the principle of charging and discharging the electric double layer capacitor.
2, the Faraday Pseudocapacitive: theoretical model first proposed by Conway, is on the electrode surface and near-surface or bulk phase two-dimensional or quasi-two-dimensional space, the electroactive substance upd, chemical adsorption-desorption occurs and a highly reversible redox reaction, generating electrode charge potential of the capacitance associated. For Faraday quasi-electricYung, the process includes not only the stored charge stored on the electrical double layer, and an electrolyte comprising an ion oxide and the electrode active substance occur reduction reaction. When the electrolyte ions (e.g., H +, OH-, K + or Li +) diffusion from the solution to the electrode / solution interface under the influence of an applied electric field, can enter the electrode surface active oxides by a reduction oxidation reaction at the interface the bulk phase, so that a large amount of charge is stored in the electrode. Reverse reaction during discharge, these ions into the oxide by the above reduction reaction will return to the oxidation of the electrolyte, while the charge stored and released through an external circuit, which is the charge-discharge mechanism of the Faraday pseudo-capacitance. .
3 ultracapacitors prominent feature
Fast
(1) charging speed, charging 10 seconds to 10 minutes up to 95 percentage of its rated capacity above;
(2) long cycle life, the depth of charge-discharge cycle times of up to 1 to 50 million times, no “memory effect”;
(3) superior high-current discharge capacity, a high energy conversion efficiency, low loss process, ≥90 high current efficiency percentage of energy cycle; high
(4) power density of up to 300W / KG ~ 5000W / KG, corresponding to 5 to 10 times the battery;
(5) raw material composition, production, use, storage and dismantling are no pollution, is the ideal green power; simple
(6) discharge line, such as a rechargeable battery without charging circuit, high safety factor, long-term maintenance-free;
(7) The ultra-low temperature characteristics, and wide temperature range of -40 ℃ ~ + 70 ℃; facilitate
(8) is detected, the remaining power can be read directly;
(9) capacity generally range 0.1F – 1000F. .
4 ultracapacitor unit description
Farah (Farad), referred to as “method”, the symbol is F.;
1 farad is a capacitive storage 1 coulomb, the bipolar plate between the electric potential difference of 1 volt 1F = 1C / 1V;
1 Coulomb is the 1A current transport in 1s power, i.e. 1C = 1A · S;
1 coulomb = 1 ampere sec ;
1 farad = 1 ampere sec / volt;
the battery (battery) 12 V 14 discharge at safe = 14 * 3600 * 1/12 = 4200 farad (F), (Note: An 12-volt battery 14 is a 6 2v14 series to the security, if the 6 into parallel fast, safe equals 2v84, is converted to 1v 168 Ah). Earth is just a capacitance value of about 1-2F.