Porous TiO₂(B)/anatase microspheres with hierarchical nano and microstructures for high-performance lithium-ion batteries

Novel hierarchical porous TiO₂(B)/anatase microspheres have been prepared by a facile solvothermal approach and evaluated as anode materials for advanced lithium-ion battery applications. The obtained porous microspheres, with diameters ranging from 2.5 to 5.5 μm, are assembled by porous TiO ₂ nanosheets with the lateral size of a few micrometers and thickness of ~13 nm; whilst, the nanosheets are formed by aggregations of nanosized primary TiO₂ crystallites (~5-7 nm). The hierarchical porous structures are verified by BET test results with a typical type-IV isotherm curve, a high surface area (~186.2 m² g^-1) and two kinds of pores (~4 and 8.3 nm). The hierarchical porous TiO₂ microspheres present excellent electrochemical performance with high Li storage capacity and excellent high-rate cycling capability (a specific capacity of 117 mAh g ^-1 at the rate of 4000 mA g^-1 after 4500 cycles), which might be attributed to the enhanced Li⁺ diffusion and electronic conductivity induced by the hierarchical microstructures, the TiO ₂(B)/anatase heterojunction, and the pseudocapacitance of TiO ₂(B). Such hierarchical porous materials might be promising for applications in advanced power type lithium-ion batteries.