Preparation method of active carbon for supercapacitor

Abstract

The invention relates to a preparation method of active carbon for a supercapacitor. The preparation method is characterized by comprising the following steps: doping brown algae with water-soluble salt, performing hydrothermal reaction on the doped brown algae and chitosan, and then performing carbonization and activation to obtain the active carbon for the supercapacitor. The active carbon for the supercapacitor prepared by the method has a hierarchical porous structure with good connectivity, relatively high mesopore content and rich surface functional groups, and shows excellent specific capacitance performance, rate capability and cycling stability in the supercapacitor.

Description

technical field [0001] The invention relates to the technical field of preparation of energy storage materials, in particular to a preparation method of supercapacitor activated carbon. Background technique [0002] The information disclosed in this background section is only intended to increase the understanding of the general background of the present invention, and is not necessarily taken as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. [0003] Carbon electrode materials are currently the most widely used electrode materials for supercapacitors. The most commonly used method for preparing activated carbon for supercapacitors is the KOH activation method, but most of the prepared materials are microporous, with small pore size and poor connectivity, and poor ion transport ability. The effective transportation of electrolyte ions in the pore structure is greatly inhibited, which not o...

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Problems solved by technology

[0003] Carbon electrode materials are currently the most widely used electrode materials for supercapacitors. The most commonly used method for preparing activated carbon for supercapacitors is the KOH activation method, but most of the prepared materials are microporous structures with small pore sizes and poor connectivity, and poor ion transport capabilities. The effective transportation of electrolyte ions in the pore structure is greatly inhibited, which not only increases the series resistance, but also reduces the specific capacitance rapidly when the supercapacitor works at a large current density.

[0004] In order to improve the defects of the pore structure of the above-mentioned preparation method, researchers use the soft / hard template method to increase the large and medium pore content in activated carbon, but the soft / hard template method has its own disadvantages that are difficult to overcome

If the hard template method is used to obtain ordered mesoporous carbon materials, it is necessary to select a suitable carbon source, but this method is not widely used, because the selected carbon precursor and the hard template must not only have a certain interaction force, Moreover, the carbon precursor must have mesopores after carbonization, and the choice of this carbon precursor is difficult.

Regardless of the hard template method or the soft template method, the template agent is indispensable, so there are disadvantages such as time-consuming and high cost in the process of preparing materials using the template method

[0005] For the template-free method, the specific surface area of ​​the carbon material prepared in the Chinese patent "Nitrogen-rich mesoporous carbon material and template-free preparation method and method and application of making working electrode" (CN201210183389.9) is only 748m 2 / g, which does not meet the requirements of excellent electrochemical performance

[0006] In addition, since a single carbon electrode is limited due to low specific capacity or low energy density, heteroatom doping can improve this problem. One of the most commonly used methods for heteroatom doping is in-situ doping. Traditional in-situ doping Due to the doping process and the selection of doping raw materials, there are often the following problems: 1) The carbon source and heteroatom raw materials are poorly contacted and mixed unevenly, resulting in poor introduction of surface functional groups; 2) The in-situ doping process introduces ionic impurities , leading to an increase in the ash content of activated carbon

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