Preparation And Research Of High Performance Graphene-based Fiber Shaped Supercapacitors

With the improvement of people’s living standards,wearable technology is booming.Among them,energy storage devices with a certain degree of flexibility and excellent performance are currently a key research priority for researchers.Fiber-shaped supercapacitors（FSSCs）,because of their unique wire-like structures,not only have the advantages of high power durability and shorter charging times and removal of standard supercapacitors,but can also be integrated with other wearable electronic devices through processes such as weaving or knitting,offering great potential in the wearable field.However,most studies on supercapacitors have focused on improving their electrochemical performance,and the key role of intermediates in the electrochemical efficiency and structural stability of supercapacitors has not been well established.Graphene is a two-dimensional substance composed of layers of carbon atoms and can act as both collector and active material when used as a supercapacitor electrode.It can solve the problem of poor current collector/active material interface contact,and has a wide range of applications in the field of supercapacitors.However,strongπ-πbonds between graphene sheets can cause severe aggregation,resulting in very limited contact with the active material/electrolyte and high resistance to ion transport,making the pure graphene fiber electrode in practical applications are greatly limited.In order to improve the problems of difficult contact at the active material/electrolyte interface of graphene-based fiber-shaped supercapacitors and its electrochemical performance.In this project,iron（III）meso-tetraphenylporphine chloride（Fe TPP）,which has high affinity with the electrolyte,was used to reduce the contact resistance between the electrode and the electrolyte and increase the electrode spacing.Therefore,the contact area between graphene electrode and the electrolyte is enlarged.At the same time,the presence of a large number of reactive groups on the Fe TPP that can undergo redox reactions can provide additional pseudocapacitance to the device.The principle of the intercalation is that Fe TPP is formed by the coordination of an aromatic macrocycle with 18π-electrons and a metal ion in the middle.It can be electrostatically adsorbed andπ-πconjugated with graphene oxide,thus attaching to the graphene oxide sheets.The details are as follows:（1）Continuous GOFs were prepared by two wet spinning systems:deionised water—acetic system acid and dimethyl sulfoxide--ethyl acetate system.The optimal spinning system was thus obtained.（2）Using different reduction methods to reduce graphene oxide fibers,the purpose is to study the advantages and disadvantages of different reduction methods,so as to select the most suitable reduction method for the subsequent research on graphene-based supercapacitor electrodes,that is,hydriodic acid solution soaking reduction.（3）Using theπ-πconjugation of graphene with iron meso-tetraphenylporphine chloride,iron（III）meso-tetraphenylporphine chloride was successfully inserted between the graphene lamellae,which hindered the re-stacking phenomenon of graphene,expanded the contact area between the electrode and electrolyte ions.The assembled fiber electrodes have high areal specific capacitance（357.54 m F/cm~2）and energy density（7.95μWh/cm~2）.