Enhancement of cyclability of urchin-like rutile TiO ₂ submicron spheres by nanopainting with carbon

Phase-pure urchin-like rutile TiO ₂ (U-TiO ₂) submicron (<1 μm) spheres composed of numerous single-crystalline nanorods are successfully synthesized using a surfactant-free wet-chemical route. In addition, a reliable mechanism for the formation of U-TiO ₂, different from the well-known "growth-then-assembly" mode, is suggested. To provide a highly electron-conducting network, the U-TiO ₂ submicron spheres are nanopainted with a conductive amorphous carbon layer. As anodes for Li-ion batteries, the carbon-coated U-TiO ₂ submicron sphere electrodes show enhanced cycling performance, maintaining a reversible capacity of 165.7 mA h g ^-1 after 100 cycles at a rate of 0.2 C; this is attributed to the provision of an efficient electron-transport path by the conductive carbon.