Hierarchically porous anatase TiO2 microspheres composed of tiny octahedra with enhanced electrochemical properties in lithium-ion batteries

Abstract

In the present work, a one-step synthetic route is developed for fabricating hierarchical anatase TiO₂ microspheres for the first time. These microspheres are composed of ultrathin rod-like structures in the radial direction, in which ultrathin rods consisted of tiny octahedra via a growth model of oriented attachment. Based on XRD and electron microscopic analyses, a mechanism for the growth of the microspheres is proposed. This material displays a large capacity of 157.3 mA h g⁻¹ at 1 C after 200 cycles and also exhibits high rate performance and excellent cycling stability. These high performance characteristics may be due to the intrinsic characteristics of the hierarchical porous anatase TiO₂ microspheres, in which the porous structure can permit facile diffusion of the electrolyte. They can also enhance the contact between the electrode surface and the electrolyte, while the ultrathin rods can shorten the transport distance of Li-ions and electrons during electrochemical cycling. At the same, the porous microsphere can also accommodate volume changes in the charge–discharge process.