Study On Structure And Properties Of Flexible Aramid Nanofibers/Graphene Electrode Materials

In recent years,the rise of wearable electronics has promoted the development of flexible energy storage devices.Due to large capacitance,long cycling life and excellent mechanical properties,flexible supercapacitors have been considered as an ideal energy storage device.Flexible electrode materials are the key component of flexible supercapacitors and hot topics of materials science these days.Due to its excellent conductivity and large specific surface area,graphene has been widely applicated as supercapacitor electrode materials.Reduced graphene oxide（RGO）has attracted much attention due to its advantages of low cost and easy fabrication.However,electrode materials based on graphene have poor mechanical due to its aggregation which limits its application in the field of flexible electrode materials.Aramid nanofibers（ANFs）are potential candidate for polymer due to its excellent mechanical properties.In this work,ANFs/RGO,ANFs/CNTs/RGO and ANFs/RGO/MXene composite films were synthesized,and the electrical conductivity,mechanical and electrochemical properties of these composite films were investigated.The major research tasks are as follows:1.ANFs/RGO composite films were fabricated with vacuum-assisted filtration,following by hydroiodic acid reduction.The effects of ANFs contents on the electrical conductivity,mechanical and electrochemical properties of ANFs/RGO composite films were studied.It is shown that when the ANFs content is increased,the electrical conductivity of composite films decreases,while both the tensile strength and volumetric capacitance gradually increase.When the mass fraction of ANFs is 25%,composite film exhibits an electrical conductivity of 1667 S m^-1,tensile strength of184.5 MPa and the volumetric capacitance of 134.4 F cm^-3(at 0.125 mA cm^-2).2.ANFs/CNTs/RGO composite films were fabricated with facile vacuum-assisted filtration.The influence of the ratio ANFs/CNTs on the electrical conductivity,mechanical and electrochemical properties were analyzed.With the increase of CNTs content,the electrical conductivity,the rate capability and volumetric capacitance of ANFs/CNTs/RGO gradually improve,while the tensile strength decreases.When the mass fraction of CNTs is 30%,ANFs/CNTs/RGO film displays the highest electrical conductivity of 2500 S m^-1,a tensile strength of 95.7 MPa and the highest volumetric capacitance of 205.9 F cm^-3(at 0.25 mA cm^-2).3.Two-dimensional titanium carbide MXene was synthesized with LiF/HCI etching method.ANFs/RGO/MXene composite films were fabricated with vacuum-assisted filtration.When the ANFs and RGO content increase,the tensile strength and areal capacitance of ANFs/RGO/MXene composite films improve,while the electrical conductivity gradually decreases.When the total mass fraction of ANFs and RGO is50%,electrical conductivity,tensile strength and areal capacitance of ANFs/RGO/MXene composite film are 20000 S m^-1,126.9 MPa and 174.6 mF cm^-2(at1 mA cm^-2),respectively.