Lithium Storage Performance of Hollow and Core/Shell TiO₂ Microspheres Containing Carbon

By Ri, Songgyun; Deng, Honggui; Zhou, Lihui; Hu, Jun; Liu, Honglai & Hu, Ying
Published in Chinese Journal of Chemical Engineering NULL 2014

Abstract

TiO₂ microspheres containing carbon have been synthesized via one-pot hydrothermal process using CTAB as the mesoporous template and nanoparticle stabilizer, Ti(SO₄)₂and sucrose as titanium and carbon precursors, respectively. Through well designed calcination, TiO₂ microspheres with various amounts of carbon-residue, such as core/shell C@TiO₂, hollow neat H-TiO₂, and hollow C/TiO₂ composites, are obtained. When these microspheres are used as anode materials for lithium ion battery, the lithium storage performance is significantly influenced by the structure and carbon-residue. With a thin shell of TiO₂ nanoparticles and carbon-residue, the capacity of hollow C/TiO₂ composite maintains as 143.3 mA·h·g⁻¹at 0.5 C (83.5 mA·g⁻¹) after 100 cycles. Moreover, after high rate charge/discharge cycles from 0.2 C to 20 C and back to 0.2 C again, the reversible capacity recovers as high as 195.1 mA·h·g⁻¹ with respect to its initial value of 205.0 mA·h·g⁻¹. The results of cycle voltammograms and electrochemical impedance spectroscopy further reveal that Li⁺ insertion/extraction processes are reversible, and the diffusion coefficient of Li⁺ in the hollow C/TiO₂ composites is much higher than those of others, because the hollow structure can act as the ion-buffering reservoir and facilitate Li⁺ transfer from both sides of the shell, and the carbon-residue in the shell improves the conductivity as well.

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