Carbon-coated titanium dioxide micro-bowls as an anode material for Li-ion batteries

• Micro-TiO2 bowls are prepared by spray-dried precursors from Ti(OR)4 sols.
• Carbon coating effects on capacity vary significantly with TiO2 morphology.
• Carbon coating improves performances of bowls with a thick wall.
• Cycling between 0 and 3 V activates carbon layer on carbon-coated TiO2.

A series of micro-sized TiO2 materials with different morphologies were synthesized via pyrolysis of spray-dried precursors, which were obtained via tetrabutyl titanate (TBT) hydrolysis reaction. The pH value of the precursor sol and its TBT content significantly influenced the morphology of the synthesized TiO2 materials but showed little effect on the improvement of lithiation-delithiation capacity. The carbon coating effect on the electrochemical performance improvement depended on the morphology of the synthesized TiO2 particles. Carbon-coated TiO2 bowls with a large thickness (1.18 μm) provide an initial Li+ insertion capacity of 310 mAh g−1 at a cut-off voltage of 1 V vs. Li+/Li, which is much higher than the carbon-coated TiO2 bowls with a small thickness (0.62 μm, capacity: 22 mAh g−1). Carbon-coated TiO2 bowls with a small thickness can be activated via lithiation-delithiation cycling between 0 and 3 V.

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