Electrolyte solution for double layer capacitor and double layer capacitor

Abstract

The invention relates to an electrolyte for a dual-layer capacitor and the dual-layer capacitor. The electrolyte for the dual-layer capacitor comprises an electrolyte and a nitrile organic solvent, wherein the electrolyte is selected from a combination of one or more of the following structural formulas, the structural formulas is shown as specification, and A is N or CH. By improving the electrolyte, the electron transmission rate of the electrolyte under a large current is improved, so that the working voltage of the dual-layer electrolyte fabricated from the electrolyte can reach 2.8-3.2V, and the indexes such as static capacitance, the power density and the cycle property can be greatly improved.

Description

technical field [0001] The invention specifically relates to an electrolyte solution for a double-layer capacitor and the 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. 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 capacitance can be stored. [0003...

AI Technical Summary

Problems solved by technology

[0004] At present, the mature commercial electrolytes for electric double layer capacitors use TEA·BF4 (tetraethylammonium tetrafluoroborate) and TEMA·BF4 (methyltriethylammonium tetrafluoroborate) as electrolytes, and acetonitrile as solvent. Energy vehicles, subway trains and other application fields have disadvantages such as low operating voltage (not exceeding 2.7V), small discharge current, poor low-temperature performance, and poor safety. 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 has become a top priority to develop an organic electrolyte solution for electric double layer capacitors with high operating voltage (3.0V) and large discharge current, and to improve the power density and energy density of electric double layer capacitors.

[0005] The Chinese invention patent with the publication number CN104134551A discloses a compound containing N-methyl-1,4-diazabicyclo[2.2.2]octane ammonium tetrafluoroborate, N-methyl-1-azabicyclo[2.2 .2] The electrolyte of octane ammonium tetrafluoroborate for electric double layer capacitors has a working voltage of 2.8-3.2V and has a certain high withstand voltage, but its cage structure has a large molecular radius, which fails to improve the performance of electric double layer capacitors. The discharge current of the electric double layer capacitor is not significantly improved, resulting in the electrostatic capacity, power density and cycle life

Images