Preparation Of Carbon Nanocomposites And Their Application In Supercapacitors

A large amount of fossil fuel needs to be consumed due to the development of the industry which have the characters of non-renewable and infectant.Therefore,exploiting new energy that with the abilities of fast charge and discharge,green environment protection and good cycle stability is of great importance.Supercapacitor is world-widely researched because of its advantages which has excellent rate performance as traditional capacitor as well as high energy density like battery.The development of electrode material,the most essential element in supercapacitor is of great importance.Currently,carbon materials and conductive polymers are the core electrode material of supercapacitor.They both have their own advantages and disadvantages.When they are applied as single electrode material,carbon material performs steady chemical properties and cyclic properties,however,the specific capacitance is low.Although specific capacitance can be strongly enhanced by conductive polymers,the poor chemical stability leads to lower steady of cyclic properties which leads to the shortage of service life eventually.In order to obtain the high electrochemical performance of supercapacitor,carbon materials?such as graphene,carbon foam?were effectively combined with polyaniline?PANI?to form nanocomposites.Three new supercapacitors were constructed in this research as follows:1.Simple and prompt preparation of graphene integrated electrode?AG?and its application in supercapacitor.Highly layered graphene integrated electrode?AG?was prepared by electrochemical activation.Scanning electron microscopy?SEM?,Raman spectroscopy?Raman?,Fourier transform infrared spectroscopy?FTIR?,X-ray powder diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?and electrochemical methods were employed to characterize AG materials.In this study,the effects of different activation time on the electrochemical performance of AG were emphasized.When the electrical activation time reached to 120 s,the AG material became highly layered and constructed a large number of three-dimensional fold structures on its surface to significantly enhance the specific surface and electrochemical properties of the AG material.The results showed that the specific capacitance of the supercapacitor based on AG material could reach as high as 314 mF cm^-2 at the current density of 0.5mA cm^-2.When the current density turned to 10 mA cm^-2,the specific capacitance of the supercapacitor could still be kept at 86%capacity after 5000 cycles,which indicated that the supercapacitor processed a durable cycle life.2.Preparation of PANI-COF-LZU1-EG nanocomposites and their application in supercapacitor.First,an integrated electrode?EG?with three-dimensional graphene structure was prepared by electrochemical stripping.After that,COF-LZU1 was loaded on the surface of EG electrode to form COF-LZU1-EG integrated electrode.The PANI-COF-LZU1-EG integrated electrode was obtained via electrochemical polymerization of PANI on its surface to construct the supercapacitor with high performance.SEM,Raman and XPS were adopted to characterize the PANI-COF-LZU1-EG integrated electrode.The results exposed that the specific surface area of the material could be significantly increased on the foundation of uniform load of COF-LZU1 on the three-dimensional graphene electrode.At the same time,PANI which was formed as three-dimensional porous structure and loaded on the COF-LZU1-EG electrode was to the benefit of increasing the specific capacitance and cycle performance.The specific capacitance of the electrode reached as high as 3748.3 mF cm^-2 at the scanning rate of10 mV s^-1 which was much higher than that of other polyaniline-based supercapacitors.3.High-performance supercapacitor based on PANI/CNT/three-dimensional porous carbon nanocomposites.First,melamine foam soaked in cobalt salt and carbonized at high temperature to obtain three-dimensional porous carbon frame material coated by CNT.PANI-CNT-CF which could be future applied in supercapacitor was obtained via loaded PANI.Not only did carbon nanotubes coated on the framework of three-dimensional porous carbon frame improve the electrical conductivity of the material,it also provided support for the loading of polyaniline,and greatly improved the electrochemical performance of PANI-CNT-CF.The results showed that the specific capacitance of the electrode was 1791.4 mF cm^-2 at a current density of 1 mA cm^-2.While the current density turned to 3 mA cm^-2,the specific capacitance could be kept above 90%capacity,which indicated that the material had a positive cycle stability when applied as electrode material for supercapacitors.