Facile synthesis of N-doped carbon-coated Li4Ti5O12 microspheres using polydopamine as a carbon source for high rate lithium ion batteries

Nitrogen-doped (N-doped) carbon-coated Li4Ti5O12 microspheres are synthesized by a solution method combined with heat treatment, in which polydopamine-coated TiO2 is first prepared and subsequently transformed in situ into N-doped carbon-coated Li4Ti5O12 microspheres. Importantly, neither templates nor rigorous reaction conditions are needed in this process that makes it simple, effective and general. The thickness of the resulting N-doped carbon coating layer can be tailored by controlling the coating time of dopamine. The optimum designed N-doped carbon-coated Li4Ti5O12 microspheres with a continuous and high electronically conducting network demonstrated superior rate performance (123 mA h g−1 at 30 C) and excellent capacity retention (136.5 mA h g−1 after 200 cycles at 10 C) when used as anode material, indicating their promising application in high-rate lithium ion batteries.