Flexible Solid Supercapacitor Based On MoS₂/rGO/CNT Composite Fiber

Energy,life,information and materials science are the main directions of human science and technology development in the 21st century.As an important part of energy technology,energy storage technology has received increasing attention.Supercapacitor（SC）is a new electrochemical energy storage device between traditional capacitors and batteries,which has many advantages such as fast charging and discharging speed,high power density,long cycle life and low environmental pollution,etc.,and has attracted the attention of many researchers.At the same time,the popularity of portable electronic devices requires flexible energy storage devices to have better adaptability.Among them,a fiber Supercapacitor（FSC）is a type of flexible supercapacitor with a fiber shape.It has the energy storage characteristics of general supercapacitors.At the same time,fibrous supercapacitors are woven and can be combined with the traditional textile industry for applications in portable electronic devices,electronic skins and other fields.However,fibrous supercapacitors cannot meet actual needs because of their lower energy density.The key factor that affects the performance of supercapacitors depends on the electrode material.Common electrode material usually includes conductive polymer,carbon based materials and transitional metal compounds After researchers found that a lot of practice,only a single use a kind of active material of super capacitor electrochemical performance is often not satisfactory This requires a variety of active material composition,create synergies,can effectively improve the electrochemical properties.Therefore,this paper uses carbon nanotube fibers as a flexible electrode substrate to assemble an all-solid fibrous supercapacitor,and improves its performance by loading pseudocapacitive active materials.Carbon nanotubes are a new type of carbon material.Its network-like structure has many excellent properties,such as excellent electrical and mechanical properties.It is an ideal electrode material.However,due to the hydrophobic and chemical inertness of the surface of the carbon nanotubes,the pseudocapacitance active material tends to fall from the carbon nanotube fibers under mechanical deformation,resulting in poor cycling stability of the device.In addition,the pseudocapacitance active material is easy to stack and cannot sufficiently interact with electrolyte ions.Therefore,in order to prepare fiber-based supercapacitors with excellent performance,graphene oxide（GO）is used as a bonding layer,coated on carbon nanotubes,and then loaded with pseudocapacitance active materials to prepare carbon nanotube fiber-based supercapacitors.Graphene oxide can significantly increase the dispersion and cycle stability of pseudocapacitance active materials.Carbon nanotube fibers were prepared by chemical vapor deposition through a tube furnace.The fibers have a unique grid porous structure and exhibit good mechanical strength and electrical conductivity.Then the carbon nanotube fibers were soaked into the graphene oxide aqueous solution to make the graphene oxide coated carbon nanotubes to obtain GO/CNT fibers,and then the electroactive material MoS₂was loaded on the GO/CNT fibers by the hydrothermal method to prepare MoS₂/rGO/CNT composite fiber electrode.The specific capacitance of the composite fiber electrode is 267 F g^-1(2 A g^-1),and the capacitance retention rate after 2000 cycles is90%.In addition,two composite fiber electrodes are assembled into a supercapacitor device with a symmetrical structure,and its specific capacitance reaches 190.4 F g^-1(93.2 m F cm^-2).The all-solid-state FSC based on composite fiber also exhibits excellent mechanical stability.The specific capacitance can still maintain 99%after being bent 1000 times continuously at a 90 degree angle.