Analysis of different characteristics between aluminum electrolytic capacitor and super capacitor

【DESCRIPTION】：Super capacitor (ultra capacitor) is also called electrical double layer capacitor (EDLC), electrochemical capacitor (EC), gold capacitor, farad capacitor, which stores energy through polarized electrolyte. It is an electrochemical element, but there is no chemical reaction in the process of energy storage, which is reversible, because the super capacitor can charge and discharge hundreds of thousands of times repeatedly. The supercapacitor can be regarded as two non reactive porous electrode plates suspended in the electrolyte. When the electrode plate is electrified, the positive plate attracts the negative ions in the electrolyte, and the negative plate attracts the positive ions. In fact, two capacitive storage layers are formed. The separated positive ions are near the negative plate and the negative ions are near the positive plate Compared with aluminum electrolytic capacitor, double electric layer capacitor has larger internal resistance, so it can be charged directly without load resistance. In case of over-voltage charging, double electric layer capacitor will open circuit without damaging the device, which is different from the over-voltage puncture of aluminum electrolytic capacitor. At the same time, compared with rechargeable battery, double layer capacitor can be charged without limiting current, and the charging times can be more than 10 ^ 6 times. Therefore, double layer capacitor not only has the characteristics of capacitance, but also has the characteristics of battery. It is a new special component between battery and capacitance The dielectric materials used in capacitors are mainly solid, which can be divided into organic and inorganic categories. According to the molecular structure, inorganic dielectric materials have microcrystalline ionic structure, amorphous structure and both structures (such as ceramics, glass, mica, etc.). Organic dielectric materials are mainly polymer structures composed of covalent bonds, which can be divided into non-polar (such as polypropylene, polystyrene, etc.) and polar (polyethylene terephthalate, etc.) according to structural symmetry. The medium used in electrolytic capacitor is the oxide film directly growing on the anode metal, which is also an ionic structure The phenomena of polarization, loss, conductivity and breakdown occur in dielectric materials under the action of external electric field. They represent the basic characteristics of dielectrics, which depend on the composition and molecular structure The polarization of nonpolar organic materials and inorganic materials with perfect and close ionic structure belong to the type of fast polarization, while that of polar organic materials and ionic crystals with relaxed structure belong to the type of slow polarization. In the former, the dielectric constant ε is low, the loss tangent TG δ is small, the temperature and frequency characteristics are good, and the volume resistivity is also high; in the latter, it is roughly the opposite. Engineering dielectric materials are not ideal dielectrics, with different degrees of impurities, defects and inhomogeneity. This is the reason of different volume resistivity ρ V and breakdown field strength EB.