Study On Dielectric Property And Applications Of Graphene Composites

Graphene and its composites have various applications in electron devices,energy storage materials,battery,electromagnetic(EM)shielding and stealth technology due to their chemical stability,excellent mechanical and electrical transport properties.The dielectric property of material could be tuned by changing physical and chemical structures,contributing to the manipulation of EM energy transmission,which have potential applications in wearable devices and microwave communication technology.In this work,dielectric performance of graphene materials at different frequency ranges and its applications in humidity sensing and broadband microwave absorption have been researched.At kHz frequency range,the influence on graphene material’s EM properties of humidity change has been discussed.It is discovered that the dielectric loss of graphene material possesses sensitive humidity response,whose sensitivity reaches 29 and 13 times that of dielectric constant and direct current conductivity,respectively.The sensitivity of fabricated graphene material is higher than of other graphene humidity sensors reported in literatures.The high sensitivity originates from the formation of new local conductive network,which results from water adsorption of porous graphene material in a humid environment.The sensitivity can be tuned though the loading of compression,and the humidity sensing is stable and repeatable in the long term,which possesses good applications in high performance humidity sensing.At GHz frequency range,the dielectric properties of graphene composite have been studied.With the help of in-situ self-assembling and structure design,a broadband absorber has been fabricated by reduced graphene oxide/none-woven(RGO/NW)composite.The absorption band with reflection loss(RL)less than-10 dB covers 2～40 GHz and 75～110 GHz,being an absorber with the widest absorption band reported in literatures.Moreover,the bandwidth with RL<-15 dB is 62.74 GHz,realizing strong broadband absorption.According to experimental results,the coupling mechanism of patterned absorber has been proposed,providing theoretical basis for the design of broadband absorber.Additionally,the fabricated flexible graphene absorber possesses stable absorption performance and good recovery,meeting the demand of multifunctional broadband absorption for microwave.