The Study Of N-doped Carbon And N-doped Porous Carbon/graphene As Electrode Materials

Supercapacitors are regarded as one of the most promising energy storage devices because of their unique advantages including high power density,long cycling life and fast charge and discharge.As electrode materials,graphene possess excellent mechanical properties,huge surface area and high electrical conductivity.However,graphene exhibit a decreasing accessible specific surface area due to the aggregation caused by strong ?-? interactions between graphene sheets.In order to improve the electrochemical properties of graphene,increasing specific surface area is the most commonly used method,but the poor wettability increases the interface resistance of the materials.In addition,incorporation of heteroatoms into graphene has also been proved as an efficient method to improve the electrochemical performance of it.However,its limited specific surface area limits its practical application.Therefore,in order to obtain high specific surface and specific capacitance of electrode material,nitrogen doped carbon and nitrogen doped porous carbon/graphene materials obtained by carbonization and activation,have attracted widespread attention.In this paper,by discussing the influence of different experimental conditions on the materials,we prepared nitrogen doped carbon and nitrogen doped porous carbon/graphite materials of high-performance,by using polyaniline(PANI)/graphene oxide(GO)composite material as the precursor,the main research content is as follows:(1)The composites of PANI/GO(PGO)was prepared in situ polymerization of aniline(Ani)on the surface of graphene oxide(GO),after adding the additional GO,the composites of graphene/PANI/graphene(GPG)was synthesized by a hydrothermal process.The morphologies and structures of the composites were further proved by SEM,FT-IR.By discussing the weight ratio,hydrothermal temperature and hydrothermal time,it is concluded that GPG 15-180-4,when be used as supercapacitors electrode material,had the best electrochemical performance with the weight ratio of PGO and GO is 15:1,under hydrothermal process at 180? for 4 h.Moreover,GPG 15-180-4 exhibited high specific capacitances of 553 F g-1 at a current density of 1 A g-1 and excellent cycling stability up to 94.2%after 1000 cycles at a current density of 20 A g-1.(2)The nitrogen-doped hierarchical and honeycomb-like porous carbon/graphene(NHPCG and NHOPCG)have been prepared by chemical activation of the composites of polyaniline(PANI)nanorod arrays/graphene oxide(GO),and GO/PANI nanorod arrays/GO,respectively,with KOH at 700?.The as-prepared NHPCG and NHOPCG possessed high specific surface areas of 2703 and 2837 m2 g-1,and their N-doping levels of 4.38 and 4.72 at%(atomic ratio),respectively.When used as electrode materials for supercapacitors,NHPCG and NHOPCG exhibited high capacitance of 465.2 and 507 F g-1,respectively,at a current density of 1 A g-1 in 1 M H2SO4 aqueous electrolytes.Furthermore,they also exhibited outstanding cycling stability up to 91.5 and 96.8%after 1000 cycles at a current density of 10 A g-1,respectively.In the present work,it was also found that GO introduced into PANI nanorod arrays/GO not only controlled the structure of N-doped porous carbon/graphene,but also enhanced the electrochemical performance of electrode materials.(3)Three dimensional dendritic fiber mesh structure of PDH,long fiber structure of PFH,folding structure of PGP and graphene/PANI hydrogel(PGH,PNGH)were prepared through hydrothermal process,by using p-phenylenediamine(PPD)to control the morphologies of materials.After the process of carbonization,KOH activation,nitrogen doped carbon and nitrogen doped porous carbon/graphene of high-performance were synthesized.PNGC and PNGPC prepared by carbonization and activation of PNGH,respectively.The as-prepared PNGC and PNGPC exhibited specific surface areas of 296 and 2244 m2 g-1,and their N-doping levels of 10.17 and 4.48 at%,respectively.When used as super capacitor electrode materials,PDC,PFC,PGC,GC and PNGC exhibited high capacitance of 267.75,311.5,280.15,187.35 and 362.15 F g-1,at the current density of 0.5 A g-1;PDPC,PFPC,PGPC,GC-a and PNGPC exhibited high capacitance of 377.2,385.1,436.7,306.2 and 485.7 F g-1,at the current density of 0.5 A g-1,respectively.After 1000 cycles at a current density of 10 A g-1,PDC,PFC,PGC,GC and PNGC exhibited cycling stabilities of 92.7,94.2,93.1,91.4 and 94.7%;PDPC,PFPC,PGPC,GC-a and PNGPC showed cycling stabilities of 91.8,94.7,93.5,84.3 and 95.3%,respectively.