Electrolyte for double-layer capacitor and double-layer capacitor

Abstract

The invention relates to an electrolyte for a double-layer capacitor. The electrolyte for the double-layer capacitor comprises an electrolyte body and organic solvent, and the organic solvent is mixed solvent of nitrile organic solvent and other organic solvent. According to the electrolyte for the double-layer capacitor, a fluorine-containing kation electrolyte is adopted, and other organic solvent is fluorine-containing organic solvent; the electrolyte body is matched with the organic solvent, and accordingly the electrolyte is good in long-time reliability and high in working voltage; by the adoption of the electrolyte, the working voltage of the double-layer capacitor can be improved, the electrostatic capacity, the power density and the energy density of the double-layer capacitor are increased, the safety performance can be improved, and thus the electrochemical performance requirement of the double-layer capacitor can be met.

Description

technical field [0001] The invention belongs to the technical field of electrochemistry, and in particular relates to an electrolyte solution for double-layer capacitors. 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. Because the distance between the two charge layers is very small (generally less than 0.5nm, far smaller than that of ordinary capacitors), and the special electrode structure is used, the surface area of ​​the electrode is increased by tens of thousands of times, so that a huge capacitanc...

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Problems solved by technology

[0004] At present, the mature commercial electrolyte of electric double layer capacitor adopts TEA·BF 4 (tetraethylammonium tetrafluoroborate) and TEMA·BF 4 (Methyltriethylammonium tetrafluoroborate) as the electrolyte and acetonitrile as the solvent, in the ever-changing application fields of new energy vehicles and subway trains, it has low working voltage (not exceeding 2.7V), small discharge current, and poor low-temperature performance , poor safety and other shortcomings, according to the capacitor related formula E=CV 2 / 2, P=V 2 / R (E, C, V, P, R respectively represent capacitor energy, capacitance, voltage, power, internal resistance), the working voltage directly affects the energy density and power density of the electric double layer capacitor, and has a great impact on various performances Therefore, it is imperative to develop organic electrolytes for electric double-layer capacitors with high operating voltage, large discharge current, poor low-temperature performance, high electrostatic capacity, and good safety, and to improve the power density and energy density of electric double-layer capacitors.

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