| Over the past decade,with the intelligent,portable and multi-functional development of wearable electronic products,new requirements and challenges have been put forward for flexible energy storage devices.Flexible supercapacitors attract wide attentions by researchers owing to their merits of such as simple structures,safe operation and environmental friendliness.How to prepare flexible electrodes and gel electrolytes with high interface stability and good compatibility through effective structural design to meet the stable energy output of flexible devices under different deformation conditions is an urgent problem to be solved.Compared with other flexible electrodes,textile-based electrodes,which can be perfectly implanted into flexible wearable electronic products due to their unique physicochemical properties,can provide a seamless solution to release the mechanical stress induced by the various deformations that frequently appear under actual wearing conditions.Highly electrical conductivity two-dimensional materials,such as reduced graphene oxide(RGO),and MXene with high specific surface area and large lamellar structure,are useful for converting common cloth fabric into the conductive fabric.As one of the typical gel electrolyte,polyacrylamide(PAM)exhibits high ionic conductivity,but it suffers from poor mechanical properties.Bacterial cellulose(BC)has the advantages of high Young's modulus,rich oxygen functional groups and good biocompatibility,and is usually used as material enhancer.Combined with the advantages of the above materials,the fabric based composite flexible electrodes were prepared with good electrochemical properties and excellent mechanical flexibility and BC/PAM gel electrolyte with good compatibility.The PPy/MXene/PMFF flexible electrode was prepared by electrostatic self-assembly of MXene using polyethyleneimine(PEI)modified polyester fabric as flexible substrate(PMFF),and then in-situ polymerization of pyrrole.It is found that the flexible electrode shows ultra-high flexibility and can be easily bent,folded,twisted and even woven into different shapes through the mechanical prope rties characterization.In addition,the resultant electrode exhibits high electrochemical performance,including areal capacitance of 1295 mF cm-2,high rate capability(82%retained from 1 to 50 mA cm-2),and long cycling life(94.8%of capacitance retained after 30000 cycles).What's more,the PPy/MXene/PMFF symmetric device exhibits a high area energy/power density of 40.7?Wh cm-2/25 mW-2 and outstanding cycling stability performance with 93.7%capacitance retention after 30000 cycles.The large–area textile electrodes(PPy/RGO/M-PEFT)and ultralong yarn electrodes(PPy/RGO/M-PEFY)were obtained via using RGO/SnCl2 embellished polyester fabric as a flexible substrate along with in-situ polymerization of pyrrole.Both of the electrodes show excellent mechanical flexibility.The areal capacitance that can be achieved for PPy/RGO/M-PEFT is as high as 1117 mF cm-2 at 1 mA cm-2.Significantly,the capacity does not decay after 10,000 charge and discharge cycles.The maximum area energy/power density of the assembled symmetrical device is 65.8?Wh cm-2 and 25 mW cm-2,respectively.Moreover,the capacitance retention is about 100%of the initial capacitance over 10000.And the flexible device can maintain a stable capacitance under different bending deformation conditions.In addition,the PPy/RGO/M-PEFY electrode also shows good electrochemical performance.The value of gravimetric,length,area,and volumetric specific capacitance of the flexible yarn electrode is 239.6 F g-1,175.7 mF cm-1,699.6 mF cm-2,and 35.0 F cm-3(0.13 mA cm-1),respectively.The maximum area energy/power density of the yarn capacitor reach a high value at 47.2?Wh cm-2/26.5 mW cm-2.The PANI/RGO/PMFT flexible electrode was developed via coating a RGO interlayer on the surface of poly(diallyldimethylammonium chloride)(P DDA)modified textile fibers.After that,a low temperature oxidation polymerization process was conducted to deposit PANI on the RGO/PMFT.Meanwhile,a BC-reinforced PAM gel electrolyte(BC/PAM)is prepared by a simple method of radical polymerization and chemical crosslinking.The resultant textile electrode exhibits both high electrochemical performance,including areal capacitance of 1221mF cm-2,long cycling performance(94.4%of capacitance retained after 10000cycles),and outstanding mechanical flexibility with capacitance retention of 97.9%after 2000 repeated bending cycles in 1 M H2SO4 electrolyte.And the obtain BC/PAM hydrogel not only showed high ionic conductivity of 125 mS cm-1,but also delivers superelasticity up to 1300%strain and toughness of 330 k Pa.The as-prepared flexible electrodes and hydrogel electrolyte were assembled into a flexible quasi-solid-state supercapacitors,and the areal capacitance can reach 564 mF cm-2 when the current density is 1 mA cm-2.What more,the excellent energy/power density are 50.1?Wh cm-2/20 mW cm-2.More importantly,the cross section microscope images of the flexible device at different bending ti mes and bending states show high interface stability and compatibility of the prepared electrodes and gel electrolytes. |
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