Effect of Heteroatom Doped Carbon Nanofibers Embedded with Titanium Dioxide for Lithium Storage Device
Recently, the interests in various energy storage devices are rapidly increased due to the popularization of electrical vehicles. As the electrical vehicle markets are sharply grown, the attention of their power sources such as lithium ion batteries (LIBs), fuel cells, and electrochemical capacitors, are rapidly increased. Among them, the LIBs have a various advantage of a high energy density, a long cycle life, a low self-discharge rate, and an environmentally friendly feature. However, for use in power source of electrical vehicles, the LIBs have major challenges of poor ultrafast cycling performance due to low energy storage kinetics. To overcome this problem, the electrode materials (anode and cathode) have been studied for improvement of ultrafast cycling performances. In particular, due to low cost and cycling stability, titanium dioxide (TiO2) is used as anode material. Also, to enhance the ultrafast cycling performance, the composites with carbon-based materials (graphite, carbon nanotube, graphene, and carbon nanofiber) are actively researched due to the advantages such as high electrical conductivity and cycle stability. Among them, carbon nanofibers (CNFs) can be regarded as suitable composite materials with TiO2 due to the high electrical conductivity, network structure by one-dimension structure, and high specific surface area. Therefore, we described TiO2 nanoparticles well-dispersed in CNFs matrix, also, and heteroatoms doping were performed to enhance the ultrafast cycling performance. Because the heteroatom doping into carbon structure offers increased electrical conductivity, caused by additional electron and high specific surface area, caused by difference of atomic radius. So, we fabricated TiO2 nanoparticles well-dispersed in nitrogen and phosphorus doped CNFs using hydrothermal, electrospinning, and carbonization for ultrafast LIBs. Also, the structural and chemical features of samples is analyzed by field-emission scanning electron microscopy (FFESEM), transmission electron microscopy (TEM), X-ray diffraction, thermogravimetric analyses (TGA), X-ray photoelentron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH). The crystal structure of samples is investigated by X-ray diffraction. Also, the electrochemical performances of LIBs are analyzed by Electro chemical impedance spectroscopy (EIS), and galvano static charge-discharge test.
Keywords - Titanium Dioxide, Carbon Nanofiber, Heteroatom Doping, Lithium Ion Batteries