Double electric layer capacitor and organic electrolyte for double electric layer capacitor

Abstract

The invention provides an organic electrolyte for a double electric layer capacitor. The organic electrolyte consists of a 0.5-2 mole / liter electrolyte and an organic solvent, wherein the electrolyte is selected from one of compounds as shown as structural formula (1) as shown in the specification; R1 is alkyl with 1-3 carbon atoms; and the organic solvent is selected from one or more combinations of a nitrile organic solvent, a carbonic ester organic solvent and a sulfones organic solvent. With the adoption of optimization of the electrolyte and the organic solvent, raw materials of the electrolyte are simple and easy to obtain; the electrolyte is high in operating voltage, high in discharge capacity and wide in application temperature range; and the electrolyte can increase the operating voltage and the electrostatic adsorption quantity of the double electric layer capacitor, thereby correspondingly improving performance indexes such as electrostatic capacity, power density and cycle life of the double electric layer capacitor.

Description

technical field [0001] The invention relates to an organic electrolytic solution for an electric double-layer capacitor and the electric double-layer capacitor. Background technique [0002] Electric double layer capacitor, also known as super capacitor, is a brand new capacitor based on the theory of interface electric double layer proposed by German physicist Helmholtz. When the electrode is charged, the surface charge of the electrode in the ideal polarized electrode state will attract the opposite ions in the surrounding electrolyte solution, so that these ions will attach to the electrode surface to form an electric double layer, forming an electric double layer capacitance. Due to the very small distance between the two charge layers (generally less than 0.5nm, much smaller than ordinary capacitors), and the use of a special electrode structure, the surface area of ​​the electrode increases geometrically to store a large capacitance. Higher than traditional capacitors...

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Problems solved by technology

However, the patent has the following significant shortcomings. First, the electrolyte described in the patent fails to increase the working voltage of the electric double layer capacitor, which is still at the same level as the traditional commercial supercapacitor electrolyte at 2.7V; secondly, the two components Both spirocyclic ammonium tetrafluoroborate and 1-methyl-3-butylimidazolium hexafluorophosphate ionic liquids have not been commercially produced in batches, especially 1-methyl-3-butylimidazolium hexafluorophosphate The synthesis route of salt ionic liquid is long and complex industrial scale-up is difficult; third, the conductivity of the electrolyte described in this patent is only 2-3.7mS / cm at room temperature of 25°C, which is far lower than the 50mS / cm of conventional electrolyte. ~56mS / cm, which will seriously affect the high-current charge and discharge of electric double layer capacitors, resulting in the biggest selling point of electric double layer capacitors - the power density is much lower; finally, the electrolyte solvent 1-methyl-3 - Butylimidazole hexafluorophosphate ionic liquid has a melting point of 10°C and poor low-temperature performance, which makes it difficult for the electrolyte described in this patent to meet the basic requirements of the working temperature of electric double layer capacitors -40-65°C

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