Research On Structure Regulation And Electrochemical Performance Of Graphene-based Film Electrodes

Graphene films'flexibility,large specific surface area?SSA?,excellent electrical conductivity and chemical stability,make it promising as excellent electrodes for flexible all-solid-state supercapacitors?ASSSCs?.Generally speaking,?-?stacking of graphene sheets with the energy storage mechanism of electrical double-layer capacitance,is bad for the improvement of energy storage performances of the graphene film electrodes.Based on the structure regulation of the graphene film electrodes,this thesis presents the hydrothermal method,template polymerization and self-assembly method to prepare different graphene film electrodes.The research on the structure regulation and optimization of the graphene film electrodes,can play a great role to develop high-performance graphene-based supercapacitors.The main work and the conclusion are described as follows:1.The possible mechanism of the crispation on the edge of graphene oxide?GO?sheets induced by 2-butanol molecules,results in a novel graphene edge-curved 3D hierarchical network structure.2-butanol molecules can reduce GO sheets and induce the crispation on the edge of GO sheets at the same time,resulting in the uniform cylindrical micropores,which can not only improve the SSA of graphene hydrogels,but also promote the electrolyte ion diffusion and transport.The assembled symmetric device based on the graphene hydrogel film electrodes,can provide a gravimetric specific capacitance of 454 F g^-1(1 A g^-1)and a volumetric specific capacitance of 517 F cm^-3(1.14 A cm^-3).2.A new route to the structure regulation of reduced graphene oxide-polyaniline?RGO-PANI?composite films is presented.By adjusting the content of manganese dioxide?MnO₂?nanowires as self-sacrificing templates in RGO/MnO₂ nanowire composite films,two different RGO-PANI nanotube composite films can be formed.The RGO-PANI?80%?nanotube composite films with a loose 3D network structure,show a high gravimetric specific capacitance of956 F g^-1(1 A g^-1).The RGO-PANI?50%?nanotube composite films with a compact layered structure,have a large volumetric specific capacitance of 722 F cm^-3(2 A cm^-3).3.Through the screening of conductive polymers,sandwiched graphene/conductive polymer composite films can be prepared for the rational regulation of 3D network structure and 3D layered structure,in order to obtain high-volume flexible ASSSCs.Compared with polypyrrole?PPy?nanotubes and PPy nanoparticles,ultrafine and water-dispersible PANI-polystyrene sulfonic acid sodium?PSS?nanoparticles can be introduced into RGO layers,to form ultrathin compact 3D layered composite films.The assembled flexible ASSSCs can provide a high volumetric specific capacitance of 217 F/cm³?0.37 A/cm³?.Based on the hydrothermal method,template polymerization and self-assembly method,the study on the structure regulation and optimization of the graphene film electrodes,has a guiding significance for pursuing high-performance graphene-based supercapacitors.