In Situ Conformal Carbon Coating for Constructing Hierarchical Mesoporous Titania/Carbon Spheres as High-Rate Lithium-Ion Battery Anodes

It is of vital importance to improve the transport of electrons and lithium ions at the same time for optimizing the rate capability of lithium-ion battery anode materials. In this work, hierarchical mesoporous titania/carbon (TiO 2 /C) spheres are fabricated via a soft method and followed by the in situ carbonation of the residual n -hexadecylamine structure-directing agent. This green synthetic method ingeniously makes the waste organic species turn into coaxially conductive carbon layers but does not compromise the high porosity of TiO 2 . The hierarchical mesoporous TiO 2 /C spheres not only effectively improve the electrical conductivity of TiO 2 electrodes but also accelerate the entry and diffusion of lithium ions. They deliver much superior rate capability compared to mesoporous TiO 2, nonporous TiO 2 /C, and nonporous TiO 2 spheres. Furthermore, synthetic conditions of solvothermal time and calcination temperature are systematically investigated. The results demonstrate that the conductive layer, porosity, and nanocrystal size all determine the rate capability of the TiO 2 electrode. This work not only represents a green and low-cost method for the synthesis of advanced TiO 2 anode materials but also constructs an advanced electrode with high electronic conductivity, high porosity, and small nanocrystals, affording an important and meaningful reference for material synthesis and electrode design.