Design And Properties Of All-solid-state Fiber-shaped Supercapacitors Based On Transition Metal Hydroxides/Sulfides

All-solid-state fiber-shaped supercapacitors as a new type of energy storage device have attracted researchers'great interests and attention owing to their advantages of the small size,light weight and good flexibility characteristics,which has great prospect in the field of wearable electronic devices and smart textile products.However,their major defect is the low energy density compared with batteries.Therefore,current researches focus on the development of wire-shaped all-solid-state supercapacitors with high specific capacitance,high conductivity and high energy density.This paper is devoted to assemble wire-shaped all-solid-state supercapacitors.We have prepared three electrodes of NW@CuCo₂S₄,Ag-CW@ZnCo-OH and CNTF@ZnCo-OH on nickel wire,conductive Ag-coated cotton wire and carbon nanotube fiber,respectively and carried out relative electrochemical tests,characterization analysis and research.The main research contents are as follows:1.Poriferous CuCo₂S₄ nanosheets were prepared on Ni wires?NW?by hydrothermal method.The NW@CuCo₂S₄ electrode material shows a remarkable performance with 367 mF?cm^-2 at a current density of 0.5 mA?cm^-2.And two NW@CuCo₂S₄ electrodes were used to assemble a symmetric wire-shaped all-solid-state supercapacitor,which displays a good performance with a high energy density of7.2?Wh?cm^-2 at the power density of 599.9?W?cm^-2.Two devices in series can light up a red LED.In addition,the fiber-shaped supercapacitor exhibits a good flexibility.These results indicates that its excellent comprehensive performance can meet the demand of practical applications in portable electronic devices.2.We have prepared nano-porous ZnCo-OH by an electrodeposition method with self-prepared conductive silver wire as the substrate and explored the influence of Zn/Co ratio and electrodeposition time on the electrode materials structure and performance.A uniform three-dimensional porous nano-sheet structure with the optimal electrochemical performance is prepared at the parameter of Zn/Co of 1:20 and the electrodeposition time of 600 s.Its specific capacitance reaches 1723.4 F?g^-1 at the current density of 1 A?g^-1.The symmetrical all solid state fiber supercapacitor with optimal pamameters Ag-CW@ZnCo-OH as electrodes shows a good electrochemical performance with an energy density of 1199.7 W?kg^-1 at the power density of 12.4Wh?kg^-1 and an excellent flexibility and mechanical stability.These properties indicate that it has a good application prospect in wearable electronic devices.3.Nano-porous ZnCo-OH was prepared by an electrodeposition method with CNTF as a substrate instead.The high specific capacitance of ZnCo-OH is maintained and the cycling performance of electrode material is improves obviously.The specific capacitance reaches 748 F?g^-1 at the current density of 2 A?g^-1 and the cycling performance as high as 110.4%after 2000 cycles.Then the CNTF@RGO with RGO on the CNTF surface was prepared by electrodeposition method at constant voltage.The CNTF@ZnCo-OH//CNTF@RGO asymmetrical all solid state fiber supercapacitor shows an energy density of 19.1 Wh?kg^-1 at the power density of 1400.3W?kg^-1 and a great cycling performance of 79.6%after 2000 cycles.This device shows a good mechanical stability,high energy density and cycle stability,indicating its great potential in the field of portable wearable electronic devices.