Carbon/Metal Oxide Composites and Their Application in Lithium-Ion Batteries
The first chapter introduces the background about energy storage and lithium ion battery. The concepts of graphene, carbon nanotube, and carbon aerogel were covered as well. Then powder-based metal oxide-carbon composite materials and binder-free CNT-metal oxide films for lithium storage applications were further elaborated. Finally, the significance of our research was summarized.
The second chapter is about freestanding and highly conductive Fe3O4/Graphene/CNT film as lithium-ion battery anodes. Iron oxide is intensively studied as a lithium-ion battery anode material due to its high theoretical specific capacity, but it has low conductivity and poor cycling performance. Herein, we present the design of freestanding Fe3O4/graphene/Carbon nanotube film via in-‐‑situ growth by solvothermal reaction, vacuum filtration and annealing methods. The film had a sheet resistance of 23 Ω/☐ and a BET surface area of 132 m2/g. The synergistic effect of graphene and CNTs provide a flexible matrix to accommodate the volume change of metal oxide in lithium ion batteries application. This lightweight film was tested without using a current collector, binder and conducting additives, eliminating unnecessary weight in the overall devices. The film shows excellent cyclic performances, and stable rate capability. The specific capacity retained 803 mAh/g at the rate of 200 mA/g after 50 cycles. This method demonstrated a promising path for flexible energy storage devices.
The third chapter discusses facile synthesis of three‑dimensional TiO2/carbon co-aerogel nanostructures and their applications for energy storage. In the field of energy storage, it is important to design new materials and understand the fundamental principles of the electrode structure. Facile synthesis of TiO2/carbon co-aerogel material via a sol-gel method was discussed. This new material was composed of a 3-D interconnected network of TiO2 and carbon aerogel. TEM, SEM, XRD, BET SA, and electrochemistry measurements were discussed. With an operating voltage between 0.05 and 3.00 V, the discharge capacity was ~400 mAh/g at 168 mA/g current density.
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