Ti³⁺ Self‐Doped Dark Rutile TiO₂ Ultrafine Nanorods with Durable High‐Rate Capability for Lithium‐Ion Batteries

Dark‐colored rutile TiO 2 nanorods doped by electroconducting Ti 3+ have been obtained uniformly with an average diameter of ≈7 nm, and have been first utilized as anodes in lithium‐ion batteries. They deliver a high reversible specific capacity of 185.7 mAh g −1 at 0.2 C (33.6 mA g −1 ) and maintain 92.1 mAh g −1 after 1000 cycles at an extremely high rate 50 C with an outstanding retention of 98.4%. Notably, the coulombic efficiency of Ti 3+ –TiO 2 has been improved by approximately 10% compared with that of pristine rutile TiO 2 , which can be mainly attributed to its prompt electron transfer because of the introduction of Ti 3+ . Again the synergetic merits are noticed when the promoted electronic conductivity is combined with a shortened Li + diffusion length resulting from the ultrafine nanorod structure, giving rise to the remarkable rate capabilities and extraordinary cycling stabilities for applications in fast and durable charge/discharge batteries. It is of great significance to incorporate Ti 3+ into rutile TiO 2 to exhibit particular electrochemical characteristics triggering an effective way to improve the energy storage properties.