Preparation And Research Of Electrode Films For High Energy Storage Devices

Due to the increasingly fashionable trend of portable and wearable electronic devices, miniaturized wireless sensor networks and other self-powered microsystems have greatly sparked the interest of scientists in recent years. In order to fit the miniaturized electronic equipment applying in biology, medicine and environmental science, the demand for microsystems with the integration of several functions has grown dramatically than ever. Especially, micro-supercapacitors serving as an independent component, which could be imbedded into the micro machining system,efficiently solved the requirement of energy storage for the functional integration devices. Therefore, it has attracted extensive attention with such novel properties. In this paper, we investigated the application of conducting polymer based on nanocomposites in micro-supercapacitor’s electrodes. The main research contents are as follows:(1) A simple, bargained and controllable vapor phase polymerization(VPP)method was employed to deposit the poly-3,4-ethylene dioxythiophene(PEDOT) films.The process conditions including the oxidant concentration, polymerization time and polymerization temperature were systematically analyzed to achieve a better performance. The result showed that process conditions had great influences on the properties of PEDOT films. In detail, some tiny holes appearing on the surface of PEDOT films could enlarge the specific surface areas and facilitate ions penetrating into/off the whole films under the ambient that the oxidant concentration, the polymerization time, and the polymerization temperature are 30%, 80 min and 30℃,respectively. The measurement of electrochemical performance on PEDOT films presented a 8.20 m F/cm2 specific capacitance.(2) PEDOT/graphene composite films were designed and prepared by the solution of vapor phase polymerization(VPP). The structure and morphology of composite films were characterized by Fourier transform infrared spectrometer, UV-visible spectrometer,Raman microscope spectrometer, X-ray diffraction diffractometer and scanning electron microscopy. The result indicated that PEDOT/graphene films with the specific capacitance of 166.37 F/cm3 were successfully deposited by the VPP method. The films presented excellent stabilities of 91% capacity of its initial charge remaining after 5500 cycles. Moreover, PEDOT and PEDOT/graphene electrode films were individuallyassembled into the “sandwich” micro-supercapacitors, and the electrochemical performances of the micro-supercapacitors were systematically evaluated.(3) Spin coating and VPP methods were utilized to designed and prepared PEDOT:PSS/graphene/PEDOT ternary films, which was identified by the results of structure and morphology tests. The electrochemical results exhibited that the ternary film had achieved the specific capacitance of 231.85 F/cm3 at a current density of 1A/cm3, and the capacity maintained 94% of initial charge after 5500 cycles. Also the interdigital micro-capacitor consisting by the ternary composite film was assembled,and a specific capacitance of 9.67 F/cm3 was obtained at a current density of 0.02A/cm3.(4) The multi-hybrid PEDOT:PSS/Mn O2/PEDOT ternary films were designed and fabricated. By investigating the structural and electrochemical properties of the hybrid films, we summarized the growth mechanism of VPP composite films. After appropriate modification applied on the substrate, the surface of the whole VPP film presented a uniform porous structure, which could enlarge the specific surface areas and enhance the electrochemical properties. At the current density of 1 A/cm3, the specific capacitance of the PEDOT:PSS/Mn O2/PEDOT ternary film was 432.42 F/cm3, which was five times greater than that of pure PEDOT film. We assembled the interdigital microcapacitor based on the ternary film as well. This micro-device achieved both excellent flexibility and high practicability with remarkably specific capacitance of13.64 F/cm3.(5) Mn O2 nanoparticles were firstly introduced on the surface of graphene oxide(GO) layers. Then the GO/Mn O2 film was reduced and interdigital electrode of LSG/Mn O2 film was patterned by laser scribing technique. At the current density of 1A/cm3, the LSG/Mn O2 film showed a 176.83 F/cm3 specific capacitance, and the assembled interdigital LSG/Mn O2-microdevice exhibited an energy density of 2.59 m Wh/cm3. Most importantly, the effective laser scribing method which contemporarily owned the fascinating characteristics of simplicity, affordability and environmental friendliness was a prospective craft for the large scale fabrication of the arrayed micro-supercapacitors.