Development of TiO2(B) and/or M (M = Si, Sn) Nanocomposites on Nitrogen-doped Graphene for Use as High-performance Anode Materials in Lithium-ion Batteries

Abstract

Emerging technologies demand a new generation of lithium-ion batteries (LIBs) that are high in power density, fast-charging, safe to use, long cycle lives, and low production cost. For anode materials, it is a challenge to obtain these mentioned characteristics. Currently, graphite is commonly used as a commercial anode material, although it has some severe disadvantages such as a low power density, a low lithium diffusion rate, short circuit, and thermal runaway issues. Therefore, battery industries are looking for new materials to replace graphite. In this work, the group IV-elements and their oxides (i.e. Si, SiO2, Sn, and SnO2), which can alloy with lithium and deliver a high theoretical capacity, have been investigated for high capacity anodes. However, problems of high-volume expansion, poor electron transport, capacity fading, and low coulombic efficiency have been mainly observed. For these reasons, another alternative anode material in the type of lithium intercalation materials has become an attractive anode. TiO2(B), which offers major advantages of a high Li-ion diffusion rate in charge-discharge processes, safety in use, and good stability. Interestingly, the pseudocapacitive behavior of TiO2(B) exhibits large channels and voids related to the size of Li-ion that result in a fast Li-ion diffusion rate during the charging/discharging. The fast charging performance is resulted. However, these materials, especially Si, SiO2, and TiO2(B), have poor electrical conductivity. This drawback could be overcome by combining with graphene-based materials. A 2D-graphene sheet, which provides stable and flexible matrices, acts as a mechanical buffering zone against the large volume change problem and also improves the cycling capability of LIBs. Furthermore, the large surface area can contain active materials and provide the conducting backbone in the structure to encourage electron transport. Interestingly, nitrogen doping, nitrogen-doped graphene, can also enhance the conductivity and specific capacity of the anode material. As an introduction, the group of Si, SiO2, Sn, SnO2, TiO2(B), and graphene-based materials were synthesized and investigated as nanocomposite materials by a facile chemical method. To study the electrochemical properties, the synthesized products were prepared as the electrode to fabricate in coin cell and then measured the battery performance, in terms of specific capacity, cycle capability, rate performances, electrochemical reaction, and adaptive fast charging capability. The synthesized nanocomposites had excellent anode characteristics, showing a potential as an anode material in advanced power batteries for next-generation applications.