Preparation Of Polyaniline/reduced Graphene Oxidized Composites And Application In Lithium Batteries

Polyaniline(PANI)is a conductive polymer formed by oxidation polymerization of aniline monomer,because of its good redox reversibility,higher theoretical specific capacity(294 m Ah/g),low cos tand environmentally friendly,so it can be used as cathode material for lithium batteries.However,for pure polyaniline molecules,the degree of conjugation is low and self aggregation is serious.Therefore,pure polyaniline has lower specific capacity as cathode material for batteries,and its reversibility is poor.In this paper,PANI/RGO and PANI/RGO/CNTs composite materials were prepared by adsorption double oxidant method with different functional reduced graphene oxidized(RGO)as template,so as to improve the electrochemical performance of polyaniline.Firstly,PANI/RGO composites were prepared by using graphene with different oxidation degree as template.Some physical characterization methods(SEM,TEM,FT-IR and XRD)were used to analyze the material,and the composite formed a layered structure with good morphology and crystallinity.The CV and EIS tests showed that the reduced state composite has better electrochemical properties.The charging and discharging tests for batteries showed that the reduced composite obtained the higher specific capacity and better cycling performance compared with the oxidized.It was confirmed that the higher discharge capacity the batteries get,the more serious attenuation the capacity became when charging and discharging tests under different current density.Secondly,the graphene materials were functionalized with different groups(carboxylic acid,oxalic acid and benzene sulfonate),then were used as the template in the preparation of the functional PANI/RGO composites,and also the PANI/RGO/AC composite was prepared while 1% RGO and 1% AC(Active Carbon)were used.The FT-IR test showed that reduced graphene oxidized and polyaniline composites with different functions behaved the characteristic absorption bands of functional groups,and the for the reduction and oxidation state of polyaniline,that the quinoid absorption peak decreased and the benzene type absorption increased prove that the material is well reduced.The SEM and XRD tests showed that the reduced composites acquired better crystallinity and regularity.Electrochemical impedance spectroscopy(EIS)tests were carried out to show that benzene sulfonate materials exhibited minimal charge transfer resistance.The CV test showed that the reduced composites possessed greater peak current density and a broader closed area.The batteries' charging and discharging tests showed that,under the current density of 0.1 C,the coulombic efficiency of batteries is close to 100%,among all of the composites,the specific capacity of discharge for the benzene sulfonic acid of the reduced composite was highest,reached 202.7 m Ah/g,and 50 charging and discharging cycles,the capacity has been reduced by 10.6%;and the cycle performance of the PANI/RGO/AC was best,for 0.1 C,50 cycles,9.6% attenuation;0.2 C,100 cycles,attenuation of 3.5%;0.5 C,300 cycles,attenuation of 24.8%;1 C,500 cycles,27.6% attenuation.Finally,RGO and CNTs were combined with PANI with changing the mass fraction of the three,and different PANI/RGO/CNTs composites were obtained.The SEM test showed that the composites had better morphology when RGO was 2% and CNTs was 5%.The FT-IR and XRD tests showed that the peak intensities of the characteristic peaks in the composites were different when the amount of RGO and CNTs was different.CV and EIS tests showed that the reversibility of the composites becomed worse as the amount of RGO and CNTs increased.At 0.2 C current density,the battery was recharged for 100 cycles,it was clear that the cycle stability of the composite was the best when the RGO was 2% and CNTs was 5%.However,with the increase of the amount of RGO and CNTs,the stability of the compo sites became worse.The preparation of the composites in the market analysis,compared with other lithium battery cathode materials,polyaniline composite material had the advantages of low cost,environment friendly,stable discharging for work,so it had a broad prospect for development in the future.