Preparation method and application of carbon nanofibers

Abstract

The invention belongs to the technical field of electrode materials, in particular to a preparation method and an application of carbon nanofibers. In the preparation process of carbon nanofibers, starch used as a pore forming agent is decomposed at a lower temperature (200-300 DEG C), and starch is decomposed in the pre-oxidation stage. After pre-oxidation and carbonization, a large number of micro-pores and mesopores will be produced with the shrinkage of fibers. Thus, the specific surface area and the porosity of the carbon nanofibers are greatly improved. When the carbon nanofibers prepared are used to make super capacitors, the specific capacitance of super capacitors can reach 70F/g, which shows that the carbon nanofibers prepared in the invention have excellent electrochemical performance.

Description

technical field [0001] The invention relates to the technical field of electrode materials, in particular to a preparation method and application of carbon nanofibers. Background technique [0002] Carbon nanofiber is a nano-sized carbon-based material obtained by electrospinning technology from polymer precursors, followed by pre-oxidation and carbonization. Carbon nanofibers have excellent nanostructure, high degree of graphitization and stable physical and chemical structure, and are good electrode materials for supercapacitors. But after pre-oxidation and carbonization, pure carbon nanofibers do not produce a rich pore structure, so carbon nanofibers have low specific surface area and porosity. [0003] The principle of carbon-based supercapacitor is the principle of electric double layer, which mainly uses the adsorption of the electrode to the electrolyte to increase the electrochemical performance. Therefore, in order to improve the electrochemical performance of su...

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Problems solved by technology

[0004] At present, there are three main methods of activating carbon nanofibers: the first method is gas activation, which continues to maintain high temperature after carbonization, and introduces carbon dioxide gas, using carbon dioxide to react with carbon at high temperature to generate pores and increase its specific surface area. ; The carbon nanofibers obtained by this method are micropores (size<2nm), compared with mesoporous (2-50nm), micropores can not greatly improve the electrochemical performance of the electrode; the second method is acid-base Salt activation, carbon nanofibers are mixed with phosphoric acid, potassium hydroxide or zinc chloride and then activated at high temperature. This method will produce a large number of mesopores, but the activated carbon nanofibers need to be subsequently neutralized. The method is not easy to control, the yield is low, the process is complex and will produce certain pollution; the third method is in-situ activation, that is, adding inorganic fillers, such as calcium carbonate, zinc oxide, etc., when preparing the spinning precursor, using inorganic fillers Pyrolysis produces pores during carbonization. This method needs to remove impurities (such as calcium oxide and zinc oxide) remaining in carbon nanofibers, and the subsequent processing steps are cumbersome.

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