Hierarchical Porous Anatase TiO₂ Microspheres with High-Rate and Long-Term Cycling Stability for Sodium Storage in Ether-Based Electrolyte

Hierarchical architecture of porous anatase TiO2 microspheres is obtained by a universal solvothermal reaction, which can improve the cycling stability and ionic/electronic transport properties in sodium-ion batteries without further coating, carbon modification, or element doping. Meanwhile, through combining the porous structure with an ether-based electrolyte, the electrochemical properties of this material have been significantly enhanced. A great specific capacity of 207.3 mA h g–1 at 1 C (168 mA g–1) after 250 cycles can be achieved. Even at an unimaginable current density of 40 C, an outstanding cycle life was achieved with a capacity of 140.6 mA h g–1 over 10000 cycles. Furthermore, in situ Raman spectroscopy and ex situ XRD pattern analyses were carried out to explore the structural transformation in the first cycling process.