Graphite has been extensively used as a negative electrode material due to its relatively high specific capacity and electrochemical stability [1-3]. However, several issues were brought about due to inherent electrochemical characteristics of graphite; electrodeposition of lithium at the surface of graphite during quick charging, and a solid electrolyte interface (SEI) layer formation by the secondary reactions between graphite and electrolyte. These problems deteriorated the performance of the graphite electrode, resulting in shorter lifetime and reduced capacity. Thus, an alternative electrode material has been actively explored to replace it. In particular, electric vehicles requiring fast charging need electrode materials not only experiencing little lattice distortions during charge–discharge cycles, but having a long lifetime, high stability, and high discharging capacity, etc. And most of all, they need to be fabricated at a reasonably low cost.
Among the promising materials to replace the graphite electrode, nano-structured TiO2 polymorphs have attracted much attention due to their high capacity and micro-channeled structure appropriate for intercalation and deintercalation of the Li ions during charge–discharge cycles [4,5]. The space existing between layers in the crystalline structure as well as within the TiO2 particles could facilitate the intercalation and deintercalation of Li+ ions during the process. Especially, TiO2(B) having relatively open structures compared to Rutile, Anatase, and Brookite has an obvious advantage for the intercalation and deintercalation of Li+ ions without severe lattice distortions [6,7]. The favorable structural characteristics of the TiO2(B) mentioned above are believed to improve the lifetime and performance of the battery [8-10]. In addition, the fabrication of TiO2(B) particles is relatively simple and easy to scale up for high volume production.
In this study, we obtained belt or wire shaped TiO2(B) particles to use as a negative electrode by a hydrothermal and heat treatment process. Ball milling process was utilized to crush the synthesized TiO2(B) particles into smaller sizes to facilitate TiO2(B)/C composites fabrication. The effects of ball mill treatment on the electrochemical performance of the TiO2(B) particles were evaluated in terms of microstructure and phase changes.