In Situ Fabrication of 3-Dimentional Li4Ti5O12/Reduced Graphene Oxide Microspheres with High Tap Density for High-Rate Lithium Ion Batteries

Spinel Li₄Ti₅O₁₂ has attracted much attention as an anode material for lithium-ion batteries because of its good Li-ion intercalation reversibility and extremely small structural changes during charge-discharge cycling. Despite these advantages, Li₄Ti₅O₁₂ is not suitable for commercial use due to its low electronic conductivity (10^-13 S cm^-1), which leads to poor rate capabiltiy.¹ Several effective ways to improve the rate capability of Li₄Ti₅O₁₂ have been reported, including reduction of the particle size to the nanoscale, doping Li, Ti, or O sites with small amounts of metal or nonmetal ions, surface modification or carbon coating, and its incorporation into composites with carbonaceous materials.^2-4

Among the various carbonaceous materials, reduced graphene oxide (RGO) or graphene nanosheets has attracted considerable interest as electrode materials for electrochemical energy storage because of their unique properties such as high electronic conductivity, large surface area, and good mechanical properties. Some recent studies have demonstrated the excellent rate capability and cycle stability of   Li₄Ti₅O₁₂/RGO nanocomposites.⁴ However, in all these reports, the lithium–titanium–oxide (Li–Ti–O)/RGO nanocomposite as the precursor for Li₄Ti₅O₁₂, was initially synthesized using a two-step or multistep process. In such multistep methods, Li₄Ti₅O₁₂ particles can be limited the available sizes and morphologies. In addition, it is difficult to fabricate the phase-pure Li₄Ti₅O₁₂ due to the formation of titanates with several other phases.⁵

Previously reported Li₄Ti₅O₁₂/RGO nanocomposites mostly have 2-dimension morphologies with low tap density.^4,5 The 2-dimentional Li₄Ti₅O₁₂/RGO nanocomposites are not suitable for commercial use because their low tap density limits the volumetric energy density. Therefore, a simple and facile synthesis of 3-dimentional Li₄Ti₅O₁₂/RGO nanocomposites with a high tap density and superior rate capability is highly desirable.

In this study, we report in-situ synthesis of 3-dimentional Li₄Ti₅O₁₂/RGO microspheres with high tap density, wherein the initial Li-Ti-O/RGO precursor is fabricated by the spray drying method in the presence of all precursors in a solution. Upon subsequent heat treatment, phase-pure 3-dimentional Li₄Ti₅O₁₂/RGO microspheres with high tap density were successfully synthesized. More detailed on the synthetic procedure, morpology, electrochemical and structural properties of 3-dimentional Li₄Ti₅O₁₂/RGO microspheres will be presented at the meeting.

 References

 

1. S. G. Doo et al, J. Am. Chem. Soc., 2008, 130, 14930.

2. N. Ohta et al, Adv. Mater., 2006, 18, 2226.

3. N. Jayaprakash et al, Appl. Nanosci., 2011, 1, 7.

4. H. K. Kim et al, Electrochem. Commun., 2010, 12, 1768.

5. H. K. Kim et al, J. Mater. Chem. A, 2013, 1, 14849