Preparation Of Graphene/Polyaniline Electrode Materials By An Electrochemical Method For Supercapacitors

With the rapid development of the social economy and science technology,energy has become into an indispensable part in human development process.As time goes on,some non-renewable energy were exhausted and caused serious environmental problems during its consumption.Supercapacitor is a new energy storage device with excellent environmental performance,high power density,safe operation process,high cycle stability.Nevertheless,the low energy density is a technical bottleneck that limits the practical application of supercapacitors.It can be obtained from the calculation of energy density that the specific capacitance and the potential window are the direct factors for the energy density.Graphene(Gr)is a double-layer capacitor material with high conductivity,large specific surface area and stable electrochemical properties.Polyaniline(PANI)is a conductive polymer with high Faraday pseudocapacitance.In order to maximize the synergistic effect between the Gr and PANI,this paper mainly focuses on improving the specific capacitance and energy density of materials.The simple preparation technology and their electrochemical properties were expored.Graphite paper(GP)and aniline(An)were used as raw materials.Gr/PANI composite was synthesized by the combination of electrochemical exfoliation and deposition on one-step method.According to the morphology analysis,PANI loaded onto the surface of folded graphene with the nanowire and distributed on the GP surface in granular form.According to the electrochemical performance test,the specific capacitance of Gr/PANI composite reaches 419 F/g at 0.5 A/g based on PANI,and which is larger than graphite paper/polyaniline(GP/PANI)based on PANI(158 F/g).When the current density increases from 0.5 to 10 A/g,the capacitance retention rate of Gr/PANI composite can reach 72%,while GP/PANI composite is only 49%.After 10000 cyclic tests,the capacitance of Gr/PANI composite can still maintain 87% of the initial value.The Gr obtained by electrochemical exfoliation was functionalized with p-aminobenzene sulfonic acid,and then electrochemical deposition of An monomer with FGr as substrate material to form functional graphene/polyaniline(FGr/PANI).The capacitance of the FGr/PANI composite based on PANI reached 792 F/g,while the NFGr/PANI was only 594 F/g at 0.5 A/g.This result proves that the structure of Gr after functionalization is more favorable for the polymerization of An.When the current density varies from 0.5 to 10 A/g,the capacitance retention rate of FGr/PANI reaches 98%,while the NFGr/PANI is only 71%.The FGr/PANI electrode material was assembled into a symmetrical supercapacitor,whose energy density and power density were up to 25.65 Wh/kg and 2250 W/kg,respectively.After 10000 cyclic tests,the capacitance retention rate is 85.7%.The FGr/PANI composite material with good energy storage stability will have high research value in the application field of supercapacitor.