Carbon Nanotube Composite Fibers For Supercapacitors And Solar Cells

Carbon nanotube (CNT) due to its excellent strength and electrical properties has a wide range of applications, particularly in the areas of energy materials which have paid much attention in recent years. The carbon nanotube fibers (CNTFs) as one-dimensional macro-structure of carbon nanotubes have high strength and electrical properties because of their unique structure. So, it can be used as an electrode for new generation batteries or capacitors as energy materials. In this thesis, we use continuous CVD-spun CNTFs as the electrodes and load it with the high-capacity polyaniline or semiconductive titanium dioxide, and applied them as anodes for supercapacitor and dye-sensitized solar (DSSC) cell respectively.By potentiodynamic electrochemical deposition, we have prepared composite CNTFs coated with uniform and compact layers of polyaniline.Electrical test result shows that the CNT/PANi fibers deposited 300 cycles (60 wt. % Pani) have the specific capacitance of 335.2 F/g at current density of 1.5 A/g, power density of 411 W/kg and Energy density was 12.2 Wh/kg. At a current density of 150 A/g the specific capacitance is still as high as 187 F/g, stayed with change after 500 chage-discharge cycles at the current density.The composite fibers also show comprehensive mechanical and electrical properties, with tensile strength of 67 MPa and conductivity of 362 S/cm. Moreover, the fiber shows a photocurrent response with the current being 5.5 ?A at 0.009 V and 50 mW/cm~2 upon irradiation of a xenon lamp.The roles of the conductivity nano-micro, the redox pseudocapacitance reducing resistance effect of polyaniline, the control of the electrochemical deposition process, in the electrochemical capacitance are discussed.The CNTF is used as the anode in replacement of the platinum wire current collector for the development of a flexible electronic knitting supercapacitor.By impregnation and calcining method, we have prepared composite CNTFs with a layer of uniform and compact film of titanium dioxide on the surface, and then coated with visible light active N719 dye. The composite fibers were assembled into the flexible fiber DSSC. The battery shows open circuit voltage (Voc) at 0.025 V, short-circuit current (Jsc) at 0.07 mA, fill factor (FF) of 0.30.