Asymmetric supercapacitor and preparation method thereof

Abstract

The invention belongs to the field of supercapacitors, and particularly relates to an asymmetric supercapacitor monomer and a preparation method thereof. The supercapacitor comprises a positive electrode, a negative electrode and a membrane infiltrated by an electrolyte, wherein the positive electrode is a current collector to which a porous polypyrrole-carbon nanotube composite (PPy-CNT) is attached; the negative electrode is the current collector to which carbon black is attached; and the mass ratio of the porous polypyrrole-carbon nanotube composite to the carbon black is 1.1-2.3. The adopted positive capacitance and negative capacitance are not equal, so that, compared with the prior art, the asymmetric supercapacitor has the advantages that the amount of a positive electrode material is significantly increased and the amount of a negative electrode material is reduced; the advantages of a PPy-CNT porous three-dimensional structure of the positive electrode can be better developed; the disadvantage that a negative electrode carbon material is relatively poor in ion diffusion ability is weakened; the voltage of the supercapacitor is increased by over 1.5 times; and the corresponding specific energy and power density are more than doubled.

Description

technical field [0001] The invention belongs to the field of supercapacitors, and in particular relates to an asymmetric supercapacitor and a preparation method thereof. Background technique [0002] Supercapacitors, also known as electrochemical capacitors, are a device for storing and transmitting electrical energy. Like batteries, they are a type of electrochemical energy storage technology. Supercapacitors have higher energy density than traditional capacitors and higher power density than batteries. Supercapacitors have been used in many small electronic devices. If they are combined with lithium-ion batteries in electric vehicles, they can greatly improve the performance of existing electric vehicles, such as faster starting and climbing speeds, faster charging, and battery life. Wait longer. [0003] In the prior art, supercapacitors generally use carbon materials as electrode materials. Carbon materials have high specific surface area but low specific capacitance,...

AI Technical Summary

Problems solved by technology

Carbon materials have high specific surface area but low specific capacitance, and the contact resistance between material particles is high. The equivalent series resistance of capacitors using carbon materials as electrodes is large, and carbon materials are relatively dense, so it is difficult for ions in the electrolyte to enter its surface. The actual utilization of the surface area does not exceed 30%

Transition metal oxides as pseudocapacitive electrode materials have good effects in improving the capacitance of supercapacitors, such as ruthenium oxide, but their cost is too high to be widely used

In recent years, it has been reported in the literature that the composite of polypyrrole (PPy) and carbon nanotube (CNT) (PPy-CNT) is used as the positive electrode active material of supercapacitors, which solves the above problems well, but the remaining problem is that, The positive working potential range of PPy in aqueous electrolyte is narrow (PPy-CNT has a potential window of -0.5-0.5V in aqueous solution, relative to Ag / AgCl reference electrode)

Supercapacitors are generally symmetrical capacitors, that is, the capacitance value and working potential range of the positive and negative materials of the capacitor are equal. This design leads to the waste of a part of the working potential range of the negative carbon material when PPy-CNT and CMPB are used as electrode materials. (According to the literature Cabot Conductive Carbon Black (CMPB) has a potential window of ‐1 to 0.5 V in aqueous solution, relative to the Ag / AgCl reference electrode)

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