Characterization for enhanced mechanical properties and energy storage performance of tin oxide nanorods-carbon fiber composites

Abstract

The use of multifunctional materials is ever increasing day by days. Multifunctional materials contain structural and non-structural functions and could improve system performances through reducing weight and volume of the system. Especially, carbon fiber reinforced composites are regarded as one of the outstanding multifunctional materials which can offer structural and electrochemical energy storage functions. Performances of carbon fiber composites are critically determined by interphase interactions between fibers and matrix. Therefore, many surface treatment methods are utilized to improve composite properties. Among the surface treatments, the whiskerization method does not degrade the carbon fiber properties via nanostructure deposition. Therefore, the tin oxide nanorods were synthesized on woven carbon fiber (WCF) surface using two step hydrothermal methods as a sort of whiskerization treatment. The SnO2 nanomaterials are widely used as energy storage devices owing to its wide band gap and high excitation energy as a semiconductor material. Therefore, the mechanical and electrochemical performances of tin oxide nanostructured carbon fiber composites were studied. In this thesis, the mechanical and electrochemical energy storage performances were characterized via tin oxide nanorods on carbon fiber surface. The tin oxide nanorods were synthesized using hydrothermal method and utilized as secondary reinforcements in composite. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) method were used for observing morphology and structure of tin oxide nanorods arrays. The improved mechanical properties of the impact absorbed energy (71.65%), ultimate tensile strength (35.07%), in-plane shear strength (49.07%) and elastic modulus (44.15%) were obtained for 70 mM of SnO2-carbon fiber composite. The structural composite capacitors were fabricated with two layers of SnO2-carbon fiber electrodes, one layer of glass fiber separator and multifunctional polymer electrolyte. The electrochemical energy storage performances were characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. Multifunctional structural capacitors were achieved 147.53 mF/g of specific capacitance, 15.06 mWh/kg of energy density, and 1.16 W/kg of power density for 30 mM of SnO2-WCF composite capacitor The SnO2 nanostructures were grown by self-assembly mechanism under high pH of about 13. The growth of SnO2 was enhanced mechanical and electrochemical energy storage performances than conventional carbon fiber composites.