| Supercapacitors are widely used in electronic devices,mobile power supply,electric vehicles and other fields owing to the advantages of high energy density,fast charging and discharging process,many cycles and wide temperature range.Electrode materials,as an important part of supercapacitors,have a great impact on the performance of supercapacitors.Therefore,the development of excellent electrode materials has become a research hotspot in this field.In this paper,the polypyrrole and graphene oxide were compounded to improve the electrochemical properties of polypyrrole and to overcome the shortcomings of polypyrrole materials.Meanwhile,the specific capacitance of graphene oxide is increased.The research contents are as follows:（1）In initial,the polypyrrole nanoparticles and nanotubes were obtained.The structure and morphology of tubular PPY and granular PPy were characterized by Fourier transform infrared spectroscopy（FTIR）,XRD and SEM.The characterization results showed that The granular PPY had clustered cauliflower-like granular structure,while the tubular PPy had obvious hollow tubular structure as the results of characterizations.The cyclic voltammetry,constant current charge-discharge and impedance of granular PPY electrode and tubular PPy electrode were measured by electrochemical workstation in a two-electrode system.The specific capacity of tubular polypyrrole was significantly higher than that of granular polypyrrole,which reaching 178.6 F·g-1 as the contrastive analysis,while the specific capacitance of granular polypyrrole is 132 F·g-1.（2）Polypyrrole/graphene composites were prepared by hydrothermal method which compounding graphene with polypyrrole nanotubes.The ratio of polypyrrole to graphene was optimized by the study of electrochemical performance.The morphology and structure of the materials were characterized by Fourier transform infrared spectroscopy（FTIR）,scanning electron microscopy（SEM）and transmission electron microscopy（TEM）.The specific capacitance values of 5:1、15:1、20:1、pure graphene and pure polypyrrole are 224 F·g-1、196.4 F·g-1、187F·g-1、184.3 F·g-1 and 178.6 F·g-1,respectively at 0.2 A·g-1 according to the analysis of the cyclic voltammetry,constant current charge-discharge,AC impedance and specific capacitance of the materials.In particular,the optimum ratio of graphene/tubular polypyrrole composites is found to be 8:1,which the specific capacitance can reach 502 F·g-1 at 0.2 A·g-1 current density and the specific capacitance of the composites has been greatly increased compared with other conditions. |
