Study On Synthesis Of The Functional Carbon Microcoils And Their Electrical Properties

The 3D-helical carbon microcoils( CMCs) like the other carbon materials have the outstanding performance of low-density, high intensity, anti-temperature,corrosion resistant, wear rubbing and conductive ability. Furthermore, due to their unique helical structure, they possess excellent mechanical properties, electrical performance and have more wide application such as micro-magnetic sensor,mechanical micro-springs, high electric conductors, hydrogen storge, catalyst support and super-capacitors electrode. In this thesis, the electrical performance of CMCs,which were prepared by chemical vapor deposition( CVD) method, were carried out.Main contents are as follows:Firstly, the high purity CMCs were successfully prepared by CVD process.The Raman spectrum reveals that the CMCs consist of graphite sheets, amorphous carbon and crystal defects and their interlayer spacing is larger than that of normal graphite structure and tubostratic graphite structure. And ID / IG=0.841 showing that the microstructure of CMCs is of poor degree of order in the long term.The impedance characteristics of aligned CMCs/silicon rubber under different loads were studied. It was found that the aligned CMCs exhibits a capacitive performance, and their impedance Z decreased with the increase of applied load.Especially, the sample with few CMCs(2%wt)have more sensitivity to the applied load. To master the regularity of the impedance variation will be helpful to use CMCs as the sensing element.In order to improve the capacitance of CMCs, Mn OOH/CMC composites were fabricated through a facile microwave heating process. As electrodes, their CV, GCD are carried out respectively. The results show that their maximal capacitance can reach396 F g-1 at 2 m V s-1. During cyclic experiment at current density of 2A g-1, the value of the original capacitance firstly decrease to 206 F g-1, then slightly rise to 220 F g-1and eventually retains 214 F g-1after 1000 cycles, which shows the CMCs with good cycling stability. The EIS of the composites reveals that the EIS is composed three parts: HFA, MFA, LF. And based on the EIS, the equivalent circuit of system is proposed for simulation analysis. All these reveal that Mn OOH/CMC is a good candidate material for supercapacitor electrode.In addition, we successfully synthesize Mn O2/CMCs composites by ectrophoretic deposition, which are characterized by XRD, Raman, XPS. Theelectrochemical performance(CV, GCD) of the composites also be studied. The results show that their capacitance can reach 115 F g-1at 5m V s-1. After 200 cycles the capacitance only change from 115 to 96.7F g-1 at current density of 2A g-1, retain89.5%, showing good cycling stability.