Ordered Fractal Structure At The Interface Of Fiber Electrode And Its Application

With the rapid development of wearable electronic technology,flexible wearable devices continue to break through the limitations of traditional flat block structure,resulting in more complex new device structures such as flexible fiber,mesh and so on.Among them,fiber-shaped devices have become a hot research topic in the world because of their light weight,bendability and torsion.It is of great scientific significance to assemble a variety of functional materials such as metal or oxide at the fiber interface to build an ordered structure,which is also the demand and inevitable trend of the development for fibrosis and flexibility devices.The ordered structure includes periodic order and self-similar order.Among the self-similar ordered structures,the fractal structure occupies an important part.Assembling a broken,branched multi-level fractal structure on the fiber electrode can provide a larger specific surface area for the fiber device and greatly improve the performance of the fiber device.Assembly of smooth and uniform functional materials on the fiber electrode can improve the transmission efficiency and flexibility requirements of fiber devices.However,the fiber electrode interface has the characteristics of anisotropy,high curvature and edge effect,which the nonlinear dynamic characteristics of the interface can be strengthened,and affect the electrode material and device structure design.Therefore,it is of great significance to construct and control the ordered structure of the fiber electrode interface.This work focuses on the growth,regulation and application of ordered fractal structure on fiber interface.Aiming at the metal fractal phenomenon of high-curvature interface such as electrode edge and fiber interface,the traditional DLA fractal growth model was modified by introducing directional motion driven by electric-field,and a fractal growth mechanism based on directional motion and random motion of electric field was proposed.Based on the enhanced method of introducing multiple fields such as electric field and flow field,three types of electrodeposition microreactors have been developed.Then,the two-dimensional thin layers,one-dimensional directional arrays,and three-dimensional arrays have been used to prepare three metal fractal structure electrode materials.Through the functional material assembly on fiber and fractal structure,the application of fiber electrode in energy devices and wearable integrated electronic fabrics was explored.Main researching results were listed as follows:(1)The fractal growth of two-dimensional thin layers on the high curvature edge of the micro-point electrode was studied.The DLA model was modified by introducing the electric field-oriented electromigration of ions,and a theoretical model of MATLAB was established.A fractal growth mechanism of the two-dimensional thin-layer metal manganese electrodeposition process based on micro-point electrode was proposed.Furthermore,an electrodeposition microreactor based on the limitation of the gas-liquid interface was developed,and a two-dimensional thin-layer manganese fractal electrode material was successfully prepared.The effects of electrodeposition conditions on the fractal structure of two-dimensional thin-layer manganese electrode,such as electrodeposition voltage,electrodeposition time and ion concentration.In addition,the application of manganese fractal structure electrode in supercapacitor was explored.(2)The fractal growth of one-dimensional directional arrays at the interface of fiber electrode was studied.Based on the theoretical analysis of directional tending to X-axis motion intensity and random Brownian motion intensity in the process of one-dimensional directional array manganese fractal structure,the one-dimensional directional array fractal growth mechanism of manganese on fiber electrode is proposed.Furthermore,a thin-layer microreactor based on directional flow field control was developed,and a one-dimensional directional array manganese fractal structure electrode material was successfully prepared.The effects of external growth conditions such as electrodeposition voltage,electrodeposition time,ion concentration and additive concentration were studied.In addition,the in-situ direct oxidation method was used to assemble nano-porous manganese oxide at the fractal interface of metallic manganese to prepare a high-performance one-dimensional directional array manganese fractal supercapacitor.When the discharge current density is 2 m A·cm^-2,the area specific capacitance can reach 653 m F·cm^-2 and the capacitance value still maintain 81%of the initial value after 5000 cycles.(3)The fractal growth of three-dimensional array at the interface of fiber electrode was studied.Based on the theoretical analysis of electric field driven directional motion intensity and random motion intensity in the process of fractal structure,the fractal growth mechanism of three-dimensional array on fiber electrode is proposed.Furthermore,a full immersion microreactor was developed,and the effects of external growth conditions such as electrodeposition voltage and electrodeposition time on the morphology of three-dimensional array nickel fractal structure electrode were investigated.In addition,three-dimensional array nickel fractal supercapacitors were prepared by using ultra-thin nano-sheet Ni O and nano-particle activated carbon as active materials.The specific capacitance of the Ni O//AC asymmetric supercapacitor can be reached 313 m F·cm^-2.The energy density and power density were 0.1408m Wh·cm^-2 and 3.01 m W·cm^-2,respectively.The supercapacitor fiber can be bent and woven into an energy fabric,which can directly drive commercial electronic equipment such as toy cars.(4)The research aimed at regulating the smooth and uniform metal coating and functional oxide film at the fiber interface.By suppressing the fractal phenomenon of electrodeposition at the fiber interface,a uniform and smooth metal coating was prepared on the fiber electrode.The effects of electrodeposition voltage,electrodeposition time and p H value on the metal coating were systematically investigated.By exploring the film forming process of fiber interface oxide materials,a method of film forming based on laser fixed-point growth is proposed.Then,the fiber-based field-effect transistor is prepared,which the I_on/I_off ratio can reach to 10³.In addition,the electronic components such as fiber sensor,fiber energy device and fiber field effect transistor can be weaved and integrated to wearable function electronic integrated fabric,which can monitor the movement of human body,sweat and environmental light in real time.