Preparation Of Three-dimensional Polyaniline Arrays/Porous Carbon Nanocomposites And Their Application In Supercapacitors

With the development of the times,the problem of energy fuel shortage and environmental pollution becomes more and more serious,and it is urgent to develop the relevant technologies of efficient and sustainable energy conversion and storage.Supercapacitors are also known as electrochemical capacitors,which have the advantages of higher power density and higher energy density compared to the traditional capacitors,and have received extensive attention and expectations..The electrode materials of supercapacitors mainly include carbon materials and conducting polymers.For supercapacitor electrode material,electric charge generally stored in the electric double layer of electrodes and the electrolyte,the specific surface area of the material is an important factor for the efficiency of supercapacitor.If the material has the appropriate porosity and structure,it will increase the chance of contact between electrolyte and electrode materials,thus improve the electrical activity greatly.Due to the carbon material itself easy to aggregate and surface electrostatic charging mechanism,the specific capacitance of carbon material is small,resulting in provide insufficient energy density.Therefore,it is very important to find suitable nanocomposites to solve these problems.In order to achieve excellent electrochemical performance,we have constructed four kinds of novel efficient supercapacitors with carbon-based materials?such as graphene and porous carbon?and polyaniline.Graphene has the advantages of large specific surface area,good conductivity,good biocompatibility,and difficulty in generating redox reactions without variable valence states.Porous carbon has the advantages of wide source,large specific surface area,and low cost.In this paper,polyaniline were loaded on the substrate of carbon-based materials by in-situ growth,electrochemical reduction,and an integrated nanocomposite electrode was constructed to improve the low dispersion of nanomaterials.At the same time,due to the integrated electrode structure,and no adhesive is required,which effectively avoids the interference of the adhesive on the electrochemical performance.The specific content includes the following four aspects:1.Three-dimensional kenaf stem-derived carbon/reduced graphene oxides integrated electrode?3D-KSC/rGO?were constructed as conductive support substrates,and polyaniline?PANI?were electrodeposited on the surface of 3D-KSC/rGO electrode and used to build high-performance supercapacitors.Scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy,Raman spectroscopy and electrochemical methods were used to characterize the 3D-KSC/rGO/PANI nanocomposites.It was found that 3D-KSC not only has a large pore structure and a large specific surface area,but also its three-dimensional structure can effectively avoid the accumulation of rGO,which improve the efficiency of 3D-KSC.The results showed that the obtained 3D-KSC/rGO/PANI supercapacitor electrode had gravimetric capacitance of 1224 F g^-11 at a current density of 0.3 A g^-1,which was far higher than most of the electrode material.The 3D-KSC/rGO/PANI supercapacitor electrode exhibited excellent performance.On the one hand,the 3D-KSC/rGO/PANI supercapacitor electrode combined the advantages of 3D-KSC?large specific surface area,good conductivity?,rGO?large specific surface area,excellent electrical conductivity?and PANI?including excellent electrical activity,well pseudo capacitance?.On the other hand,it not only could make up for rGO?smaller capacitance,reunion effect?and PANI?poor stability?,but also improve the effective utilization of active materials,electrical conductivity and mechanical strength.The obtained performances of the 3D-KSC/rGO/PANI proves that the proposed supercapacitor electrode have promising future in energy storage utilizations.2.Three-dimensional porous carbon?PC?with a porous structure derived from metal-organic framework?MOF-5?without any carbon source was proposed and then PANI was polymerized on it in situ by chemical oxidation to obtain PC/PANI nanocomposites.The as-prepared PC/PANI nanonanocomposites were characterized by scanning electron microscopy,Fourier transform infrared spectroscopy,Raman spectroscopy,N₂ adsorption-desorption isotherms,X-ray powder diffraction and electrochemical techniques.It was found that PC was covered by lots of PANI and partial PANI went through the PC,which improved the electroconductivity of the nanonanocomposites greatly.The excellent performance originating from the synergistic effect of PANI?including excellent electrical activity,well pseudo capacitance and good chemical doping/undoping?and PC?including large specific surface area,hierarchical porous nanostructures and good electroconductivity?,which offersthepossibilityofhighspecificcapacitancefortheproposed nanonanocomposites.The PC's unique pore structure not only improved active sites for PANI loading but also prevented the collapse of electrode material.Under the current dentisity of 0.5 A g^-1,the PC/PANI supercapacitor electrode exhibited a specific capacitance of 1319.5 F g^-1.The specific capacitance maintained 81%after2000 charging/discharging cycles.It has potential application in the construction of capacitors.3.A novel covalent organic framework?COF-LZU1?/three-dimensional porous carbon?3D-KSC?nanocomposies were prepared.And then polyaniline?PANI?was polymerized on 3D-KSC/COF-LZU1 by chemically oxidized method to obtain the3D-KSC/COF-LZU1/PANI nanocomposites,which was used to build high performance supercapacitors.The 3D-KSC/COF-LZU1/PANI nanocomposites were characterized by a series of characterization techniques such as scanning electron microscopy?SEM?and electrochemical methods.The SEM results showed that the crystal structure of newly synthesized nanocomposites were consistent with the original COF-LZU1.PANI was successfully polymerized on the surface of3D-KSC/COF-LZU1 to form a three-dimensional structure,which was benefit for increasingthespecificcapacitanceandcycleperformanceofthe3D-KSC/COF-LZU1/PANI electrodes.The electrochemical performance of the nanocompositeswasinvestigated.Theresultsshowedthatthe3D-KSC/COF-LZU1/PANI electrode had a capacitance of 583 mF cm^-22 at a current density of 0.1 mA cm^-2,which was higher than most of the electrode materials,and the resistance was also small.After 2000 cycles of charge/discharge at the current density of 0.1 mA cm^-2,the specific capacitance still retained 81.5%,which proving that the nanocomposites had outstanding cycling stability.Excellent electrochemical properties make the electrode materials have potential application in the supercapacitor.4.A flexible electrode based on melamine foam?MF?-derived macroporous carbon and graphene oxide?3D-FC/GO?for loading Schiff base-derived carbon nanocomposites?CNDS?and polyaniline?PANI?were employed for supercapacitor research.3D-FC/GO/CNDS/PANI was fabricated for the first time.The commercial MF was prepared into ultralight and elastic 3D-FC by high temperature carbonization,and then the GO was uniformly distributed into 3D-FC to form 3D-FC/GO by soaking into GO solution.The as-prepared 3D-FC/GO flexible integrated electrodes were used to load carbon nanomaterials derived from Schiff base?CNDS?/polyaniline?PANI?nanocomposites.The obtained ultralight and elastic 3D-FC/GO/CNDS/PANI was characterized by scanning electron microscopy,Fourier transform infrared spectroscopy and Raman spectroscopy.The results showed that the uniformly distributed GO connected the broken fibers of 3D-FC produced in the high temperature carbonization to improve the electrical conductivity and also enlarge the specific surface area of nanocomposites.PANI was vertically arrayed on3D-FC/GO/CNDS.The as-prepared 3D-FC/GO/CNDS/PANI exhibited a rapid electron transport.3D-FC/GO/CNDS/PANI showed good electrical performance with a specific capacitance of 2814.5 F g^-11 at the current density of 0.5 A g^-1.It has potential application in the construction of capacitors.