Preparation And Super-capacitive Performance Of Flexible 3D Carbon Network/High-Loading Active Materials Composite Electrodes

Flexible supercapacitors possess the advantages of high power density,rapid charge/discharge rate and ultra-long service life,as well as good deformability.They are designed to be used as energy storage devices for wearable electronic products.However,loading of electrochemically active materials in flexible supercapacitor electrodes is generally very low,which leads to a unsatisfactory energy density of corresponding supercapacitors,while enhanced active material loading always brings difficulty for electron and electrolyte ion transmission and uncontrolled aggregation of nano-scaled active materials.The present work studied the issue of ’uniform distribution and effective utilization of high-loading active materials inside flexible electrodes’ from the perspectives of activation of electrode substrate,construction of 3D conductive and porous network and multi-position distribution of active materials.Based on these,high-performance and flexible supercapacitor electrodes were fabricated.Firstly,physicochemical characteristics,electrochemical property and mechanical flexibility of active carbon fiber(ACF)fabrics were investigated.Considering that ACF fabrics have relatively good electric-double layer capacitive performance and good flexibility,using them as electrochemically active substrates for flexible supercapacitor electrodes may be put forward,which is beneficial for solving the problem that commonly used inert substrates tend to cause a low capacitance of the whole flexible electrodes.ACF fabrics have a relatively poor electrical conductivity,resulting in modest rate capability.Therefore introducing carbon nanomaterials into ACF fabrics was proposed.As a result,the 3D carbon network constructed by ACF substrate and carbon nanomaterials significantly enhanced electrical and electrochemical properties of the flexible ACF/carbon nanomaterials all-carbon composite textile electrodes.Then,pseudocapacitive materials,including manganese dioxide and polyaniline,were deposited on the above 3D ACF/carbon nanotube(CNT)network to prepare high-performance flexible textile electrodes.Effects of the loading and micro-morphologies of active materials on the physicochemical characteristics and electrochemical performances of fabricated composite textile electrodes were carefully investigated.In specific,conductive polyaniline was deposited on ACF surface and in the space between ACFs(on CNT network).The multi-position distribution ofelectrochemically active materials(including ACFs and polyaniline)makes high-loading active materials can uniformly disperse inside flexible textile electrodes;in the meantime,excellent electrical conductivity and porous structure of 3D ACF/CNT network are conducive to electron movement and electrolyte ion transmission,which benefits effective utilization of active materials.Consequently,the prepared ACF/CNT/polyaniline composite textile electrodes displayed good super-capacitive performance and mechanical flexibility.Further,the high-performance flexible ACF fabric based composite textiles were dismantled into fiber bundles.The obtained fiber bundles are similar to those textiles in micro-structure,and unsurprisingly,they also exhibited outstanding electrochemical performance and flexibility as fiber-like electrodes.That is,it was realized to simultaneously produce high-performance textile electrodes and fiber-like electrodes.Finally,the strategy of ’multi-hierarchical construction of electrodes’ was adopted to prepare multi-layered CNT-polyaniline composite networks/paper electrode with large areal capacitance,good rate capability and high flexibility.Furthermore,paper electrodes were also utilized to fabricate breathable and flexible supercapacitors.In summary,the proposed strategies of ’electrochemically active substrate’,’3D carbon network’ and ’multi-position distribution of active materials’ make it possible for uniform dispersion and effective utilization of high-loading active materials inside flexible electrodes.The present work is believed to bring new ideas to fabricate high-performance flexible supercapacitors and some other energy storage devices.