With the expanding the market of lithium-ion battery (LIBs) from portable electronic devices to electric vehicles and energy storage system (EES), the improvement on their energy density, power density, safety, and cost should be highly necessary. Among the promising anoode materials for LIB, Li₄Ti₅O₁₂ has various advantages, such as high theoretical capacity (175 mAh g^-1), good Li-ion intercalation reversibility, and extremely small structural changes during charge–discharge cycling.

Despite these advantages, Li₄Ti₅O₁₂ is limited for use of LIBs 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

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.³ However, previously reported Li₄Ti₅O₁₂/RGO nanocomposites mostly have 2-dimension morphologies with low tap density.³ 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 micrometer-sized spherical Li₄Ti₅O₁₂/RGO composites with a high tap density and superior rate capability is highly desirable. 

In this study, we report one-pot synthesis of micrometer-sized spherical Li₄Ti₅O₁₂/RGO 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 micrometer-sized spherical Li₄Ti₅O₁₂/RGO with high tap density was successfully synthesized. More detailed on the synthetic procedure, morpology, electrochemical and structural properties of micrometer-sized spherical Li₄Ti₅O₁₂/RGO 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] H. K. Kim et al, Electrochem. Commun., 2010, 12, 1768