Synthesis And Electrochemical Performance Of Graphene/Polyaniline Composites For All-solid-state Flexible Supercapacitors

With the rapid development of economy in modern society,energy consumption is rising,especially non-renewable fossil fuels,which has brought enormous social and environmental problems.Developing novel energy storage devices with high energy density,high power density and long cycle life is an urgent research problem,which has caught more attention worldwide.Supercapacitor has presented the advantages of environmental friendly,fast charge-discharge process,high power density and long cycle life in the fields of new green energy storage devices,which has got the favor of many researchers.But,due to its low energy density,supercapacitors?SCs?also exist disadvantages and shortcomings in energy storage,which is adverse for developments in many fields,such as emerging intelligent electronic equipment,transportation tools,military equipment,field operation,tanks and aircrafts,etc.The issues to improve the energy density of new type energy storage device,cyclic stability and power density and reduce the production cost,have become fiery research topics for scientific workers.As is known to all,high power density and cyclic stability is the most significant advantages for supercapacitors,but the low energy density limits a lot.Based on the energy density formula?E = CV²/2?,we can see that there are two ways to improve the energy density,including improving the specific capacitance and increasing the working potential window.Supercapacitor electrode materials are the key points to improve the specific capacitance.Therefore,we conducted the experiments based on our experimental conditions and the research background of the project group.In this paper,we mainly did some researching of 3D graphene?r GO?,which owns excellent conductivity,chemical stability,robust nanostructure and large specific surface area.But the specific capacitance of that is low generally.According to that,lots of researchers choose to composite graphene with polymer to improve the electrochemical performance.Moreover,to improve the applied value of flexible supercapacitors,the properties of mechanical stability and excellent flexibility are exactly needed.Therefore,we fabricated the 3D graphene aerogel via self-assembled and then composite that with polyaniline?PANI?by electrochemical deposit to improve the whole electrochemical performance.The details are as the following.Firstly we prepared 3D graphene from 2 mg ml^-1?5 mg ml^-1?10 mg ml^-1 graphene oxide solution,and got the specific capacitance of each solution which is 230 F g^-1?195 F g^-1?162 F g^-1,respectively.The coulombic efficiency of 2mg·ml^-1 3D graphene film is 93.2% after 10000 cycles.In the second step,a new synthetic strategy was developed for enhancing the electrochemical performances of r GO aerogel-based SCs via electrodeposition polyaniline arrays on the surface of ultralight r GO aerogel.This novel hybrid composites can take full advantage of the rich open-pore of 3D r GO aerogel and high capacitance contribution from the PANI.The obtained hybrid composites exhibit excellent electrochemical performance with a specific capacitance of 432 F g^-1 at the current density of 1 A g^-1,robust cycling stability to maintain 85% after 10000 charge/discharge cycles and high energy density of 25 W h kg^-1.Furthermore,the flexible all-solid-state SCs have superior flexibility and outstanding stability under different bending states.The high-performance flexible all-solid-state SCs together with the lighting tests demonstrate it possible for applications in portable electronics.