Preparation Of Polyaniline/Graphene Composites And The Electrochemical Performance For Supercapacitors

The development of high-performance supercapacitors is mainly dependent on the research of high-activity electrode materials.Polyaniline?PANI?is considered as the most promising candidate among conducting polymers for supercapacitors due to its highest theoretical specific capacitance,high environmental stability,ease of synthesis,and low-cost manufacturing.But the drawbacks associated with PANI are its low realistic specific capacitance and poor cycling stability,which hinder its commercialization.In this paper,graphene oxide?GO?was prepared using the modified Hummers method.Reduced graphene oxide?rGO?derived from GO was synthesized by chemical reduction assisted by hydrazine hydrate and GO was functionalized with sulfonic groups to obtain sulfonated graphene?SG?.PANI/GO,PANI/rGO,PANI/SG,and PANI/GO/CNTs composites were prepared by an in situ chemical oxidative polymerization method with different graphene materials as template,so as to improve the electrochemical performance of polyaniline,and the contents of this paper are following aspects:First,the combination of PANI and graphene materials circumvented the phenomenon of aggregations especially in the PANI/SG composite.The CV tests showed that the PANI/SG based supercapacitor possessed good electrochemical reversibility and higher specific capacitance but lower internal resistance.The specific capacitance of PANI/SG electrode was as high as 219.5 F/g and higher than that of PANI at current density of 0.5 A/g.Besides,the rate capability and cycle stability of the electrode were improved by 8.2%and 17.9%,respectively.The EIS tests showed that the PANI/SG based supercapacitor had the lowest charge transfer resistance and represented better capacitive behavior.After 5000 charging and discharging cycles,the capacitance decreased to 90.2%of initial capacitance,demonstrating that PANI/SG electrode exhibited excellent cycle stability.Second,GO and CNTs were introduced to modify PANI doubly.By comparing the morphologies of PANI when the graphene materials,as template,were present or absent,it can be found that PANI was distributed more uniformly in the form of small size.The entangled CNT forests sandwiched between GO layers restrained the aggregations of GO layers and built a bridge for electron migration inside the material.The XRD tests revealed that the material possessed good crystallinity and regularity,which were beneficial to obtain better electrochemical cycling stability.These components acted synergistically inside the material,obtaining outstanding electrochemical properties,including high specific capacitance?197.6 F/g at 0.5A/g?,good rate capability?86.8%capacity retention when the current density was increased by 10 times compared with the initial?and excellent cycling stability?90.7%capacity retention after 5000 cycles?.Next,PANI/GO/CNTs was used to assemble supercapacitors to investigate its capacitive performance in 1 M LiClO₄/AN organic solution.According to the electrochemical results,the asymmetric supercapacitor?ASC?exhibited an acceptable specific capacitance up to 39.4 F/g at 0.5 A/g and the energy density of the supercapacitor was 28.9 Wh/kg.Furthermore,the capacity retention of the ASC remained 86.3%over 500 charging and discharging cycles and the ASC possessed about 27%deterioration of the initial specific capacitance after 2500 cycles,implying its potential for practical application in energy storage devices.Last,the current situation of the supercapacitor industry and the market potential of polyaniline-based supercapacitors were analyzed.It was found that the development of foreign supercapacitors started early and the technology was relatively mature but the industrialization of domestic supercapacitors was in the incipient stage.PANI based materials used as electrodes had the advantages such as low cost,so they showed extraordinary prospects for the application of supercapacitors.