| In order to meet the requirements of high power density, supercapacitors with high power density attracted researchers’ attention naturally. And the development of excellent electrode materials for supercapacitor is the main objective of the current study.In this paper, we use a coaxial electrospinning method to prepare the composite fiber with a core-shell structure:titanium nitride (TiN) as the core, and materials of pseudocapacitance as the shell. TiN-VN composite fiber’s shell is vanadium nitride (VN). And the shell of TiN-MnO fiber is manganese oxide (MnO). The materials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron diffraction (XRD), X-ray spectroscopy (EDS), physical adsorption and other means of testing. The super capacitive behavior of these materials are studied by using three-electrode system. We carry out cyclic voltammetry (CV), charge and discharge and AC impedance measurements. The main work is as follows:Tetrabutyl titanate [Ti(OC4H9)4] and acetylacetone manganese[Mn(C5H7O2)3] as raw material, we prepared TiN-MnO fibers of core-shell structure by coaxial electrospinning. And we characterized its structure and electrochemical properties by testing. The SEM images demonstrated that thesurface of as-prepared TiN-MnO fibers were smooth, continuous one-dimensional structure with a diameter of about1μm, and after high-temperature treatment under ammonia, the fibers became thinner and shorter, about600nm in diameter, and the surface was rough with holes. TEM test exhibited the fibers with a typical core-shell structure, and a thin carbon layer on the their surface. The BET surface area of TiN-MnO fiber was16m2/g. The TiN-MnO fiber was composed of pure phase TiN and MnO by XRD, there was no other impurity phase. Supercapacitor performance test concluded that the rate capability of TiN-MnO improved significantly compared to MnO. The cycling performance can also be accepted with trace capacity fade. The EIS test was used to explain the fade of capacity during cycling. TiN-MnO was a potential electrode materials for supercapacitor, but it needed further research and development.Ti(OC4H9)4and acetylacetone vanadium [V(C5H7O2)3] as raw materials, we prepared TiN-VN fibers with core-shell structure by coaxial electrospinning. We determined the different proportion of vanadium and titanium fiber by electrochemical characterization. We found that the fibers (V:Ti≈1:2) had the best performance, and this ratio was the main object of research. SEM and TEM images proved that fiber was the obvious one-dimensional structure, and of varying lengths, the diameter of fiber was about1μm. After high temperature treatment (800℃) under ammonia, the TiN-VN fiber became thinner and shorter and very rough, composed of granular structure. And the diameter of fiber was about500nm, with a core diameter of about300nm. The TiN-VN fiber was polycrystalline and coated with amorphous carbon by HRTEM characterization. The carbon of TiN-VN was about13%by elemental analysis. XRD analysis exhibited the formation a vanadium-titanium solid solution. The specific surface area of TiN-VN was up to169m2/g by BET, and average pore size was about3nm. By cyclic voltammetry (CV), TiN-VN could combine the advantages of TiN and VN which showed excellent rate capability and good capacity. After500cycles, the capacity retention was88%. EIS and XPS explained that the capacity fading after cycles was caused by partial oxidation of TiN-VN. |
PDF Full Text Request