Ultrathin nanobelts-assembled Chinese knot-like 3D TiO₂ for fast and stable lithium storage

Nanostructured TiO₂ has applications in solar cells, photocatalysts, and fast-charging, safe lithium ion batteries (LIBs). To meet the demand of high-capacity and high-rate LIBs with TiO₂-based anodes, it is important to fine-tune the nanoarchitecture using a well-controlled synthesis approach. Herein, we report a new approach that involves epitaxial growth combined with topotactic conversion to synthesize a unique type of 3D TiO₂ nanoarchitecture that is assembled by well-oriented ultrathin nanobelts. The whole nanoarchitecture displays a 3D Chinese knot-like morphology; the core consists of robust perpendicular interwoven nanobelts and the shell is made of extended nanobelts. The nanobelts oriented in three perpendicular _A[001] directions facilitate Li⁺ penetration and diffusion. Abundant anatase/TiO₂-B interfaces provide a large amount of interfacial pseudocapacitance. A high and stable capacity of 130 mA·h·g^-1 was obtained after 3, 000 cycles at 10 A·g^-1 (50 C), and the high-rate property of our material was greater than that of many recently reported high-rate TiO₂ anodes. Our result provides, not only a novel synthesis strategy, but also a new type of 3D anatase TiO₂ anode that may be useful in developing long-lasting and fast-charging batteries.