Construction Of Graphene Modified Textile Based Flexible Supercapacitors And Research On Smart Wearable Application

Recently,with the great demands of artificial intelligence sensing system and energy transmission and storage system,smart wearable textiles have been rapidly developed and become one of the research hotspots.Smart textiles could generally be divided into two categories:smart sensing textiles and flexible energy storage textiles.And in the smart textile applications,the preparation of highly flexible supercapacitors and seamless integration with textile is one of the most important factor,therefore,various flexible substrate materials have been applied to assemble flexible supercapacitor,such as paper,sponge,film,fiber,fabric and other flexible materials.Among all these cases,the fabric with unique textile structure is considered to be the most perfect material for fabricating wearable flexible supercapacitors due to its excellent flexibility,elasticity and seamless integration with textiles,and it has become a research hotspot in the field of flexible supercapacitors.However,the energy storage performance of two-dimensional flexible supercapacitor is closely related to the textile substrate used and the performance of traditional flexible supercapacitors based on textile fabric are often limited because the active material can only exist on the fabric electrode surface in the form of block coating.Consequently,the energy storage performance of the assembled devices can be effectively improved by selecting the flexible supercapacitors with more fibrous and porous fabrics and larger contact area of active materials.In this paper,the textile-based flexible SCs based on cellulose non-woven fabric and multidimensional hierarchical fabric were fabricated via a structure design method.The assembled flexible devices exhibited enhanced energy storage performance which realized by the effective combination between electrochemical active materials and fabric substrate.The main research contents of this paper are as follows,?1?Cellulose nonwoven fabric was selected as substrate for the preparation of flexible supercapacitor,and graphene was deposited on the surface of cellulose nonwoven fabric by a capillarity-assisted assembly coating method,which solved the shortcoming of traditional woven fabric and knitted fabric with compact structure and difficulty in introducing active materials into the fabric.And the graphene and MnO₂deposited fibrous nonwoven fabric electrodes were fabricated after depositing the MnO₂ nanoparticles on graphene modified fabric.The experimental results showed that the assembled fabric electrodes exhibited good electric conductivity,excellent flexibility,a high specific capacitance of 453.4 mF/cm²,outstanding cycle life and bending properties of remaining 82.5%of the initial capacitance for 5000 CV cycles.?2?To further evaluate the influence of fabric contact area on the energy storage performance of flexible supercapacitor,the multidimensional hierarchical fabric was selected as the substrate to fabricate textile-based flexible supercapacitor.Graphene and poly?3,4-ethyl-enedioxythiophene?/poly?styrenesulfonate??PEDOT:PSS?were deposited on the hierarchical fabric via a spraying method.The experimental results show that the micro-fiber array structure on multidimensional hierarchical fabric could effectively improve the available area between the fabric and the active material,load more active material in the unit area,and promote the diffusion rate of ions in the electrolyte during the electrochemical reaction.?3?In order to further exploit the advantages of multidimensional hierarchical fabric structure,the flexible fabric electrodes were prepared by depositing polyaniline onto the surface of multidimensional hierarchical fabric by electrochemical polymerization.Experimental results show that by controlling the electrochemical polymerization time,the synthesis of polyaniline?PANI?could be effectively controlled.And the PANI/G@HF exhibited excellent electrochemical performance,the areal specific capacitance reached to 3382.5 mF/cm².The ultra-high areal specific capacitance fully demonstrates the potential application of electrochemical polymerization of PANI/G@HF in the preparation of high-performance textile-based flexible supercapacitors,which provides an effective new idea for improving the performance of flexible supercapacitors?4?Meanwhile,the graphene and MnO₂ deposited fibrous nonwoven fabric electrodes were fabricated after depositing the MnO₂ nanoparticles on graphene modified fabric.The experimental results showed that the assembled SC exhibited good electric conductivity,excellent flexibility,a high specific capacitance of 138.8 mF/cm²,outstanding cycle life and bending properties of remaining 87.6%of the initial capacitance under 180°bending angles for 1000 cycles.What's more,the single graphene/PEDOT coating hierarchical fabric?G/PHF?electrodes were assembled to fabricate a symmetrical fabric-based all-solid SC?G/PHSC?.And the bionic assembled SCs exhibit enhanced specific areal capacitance of 245.5 mF/cm² at 1 mV/cm²,high energy density 21.82?Wh/cm² at 0.397 mW/cm² compared with 2D fabric-based SCs?41.6 mF/cm²?.Besides,the SCs also maintain a stable capacitance ratio of 83.9%after10000 cycles and merely capacitance loss under different bending states.As a proof of the concept,an smart electronic fabric switch is fabricated with self-power and wearable properties,along with some other trial applications.Such hierarchical fabric with the bionic fiber micro-array structure is believed to enhance the performance of the assembled SCs.And we foresee that the multidimensional hierarchical fabric would bring broader application prospects for flexible energy storage devices and smart wearable electronic textiles.Generally speaking,to solve the problem of the tight structure of traditional fabric which makes it hard for electrochemical active material closely to the interior fabric and the low contact area in process of electrochemical reaction,the flexible textile-based SCs were developed in this paper based on graphene/MnO₂ modified cellulose non-woven fabric,graphene/PEDOT modified multidimensional hierarchical fabric and graphene/PANI modified multidimensional hierarchical fabric.The assembled devices were further evaluated and applied for smart wearable devices,which exhibited excellent energy storage performance and potential applications of the flexible wearable electronic devices and has potential application in intelligent textiles.