A method of adsorbing and hydrolyzing polyimide molecules on graphene surface to improve specific capacitance

Abstract

The invention belongs to the preparation field of an electrode material of a high-energy-storage graphene-based supercapacitor. Based on the advantages of large specific surface area, high electron mobility and the like of graphene, the graphene becomes an ideal capacitor material; however, the actual specific capacitance of graphene is greatly lowered caused by high probability of stacking and agglomeration of graphene laminated layers, low dispersity in a solvent, incomplete reduction of an oxygen-containing functional group and the like. A uniform dispersion solution of liquid crystal graphene oxide / ammonium carbonate / sodium chloride / CVD graphene at certain mass ratio is dropped in a polytetrafluoroethylene die with controllable dimensions, and then steps of flattening, drying and film forming are performed; next, a hydrothermal reaction is performed in ammonium hydroxide and polyimide solution of a certain concentration; and then, a high-specific-capacitance nitrogen-doped graphene thin film electrode material is prepared by a low-temperature heating method. By virtue of the method, large-scale and low-cost high-energy-storage graphene can be prepared; and the specific capacitance and energy densely of the graphene-based supercapacitor can be improved, so that the commercial application of the graphene-based supercapacitor can be further promoted.

Description

technical field [0001] The invention relates to a method for increasing the specific capacitance by adsorbing hydrolyzed polyimide molecules on the surface of graphene, which belongs to the field of graphene-based supercapacitors, in particular a technology for introducing pseudocapacitive components to improve the specific capacitance of graphene electrodes. Carbon-based supercapacitors, also known as electric double layer capacitors, rely on the physical adsorption and desorption of ions on the surface of porous electrodes to charge and discharge. This invention hydrolyzes the high-temperature-resistant plastic polyimide film commonly used in the industry, and the small organic molecules released into the water are adsorbed to the surface of graphene through π-π interaction. Such organic molecules can undergo reversible redox reactions with aqueous electrolytes during charge and discharge. In this way, when the weight of the graphene material increases by about 3% after ads...

AI Technical Summary

Problems solved by technology

However, such materials often have high resistivity and need to be attached to the surface of porous conductive materials, and when the active material loading per unit area increases, the specific capacitance will decrease significantly.

Conductive polymer pseudocapacitive materials with narrow voltage window and short cycle life

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