Microscale spherical carbon-coated Li4Ti5O12 as ultra high power anode material for lithium batteries

Abstract

Microscale C-Li₄Ti₅O₁₂ particles with high tap density were synthesized by a simple solid-state reaction using TiO₂, Li₂CO₃, and pitch. The effect of the carbon content on the physicochemical and electrochemical properties of this material was extensively studied. On calcination of the particles at high temperature in an inert atmosphere, the uniformly coated carbon layer from pitch inhibited the growth of primary particles, maintaining the spherical morphology, similar to the TiO₂ precursor in size and shape, and also enabling partial reduction of the starting Ti⁴⁺ to Ti³⁺. Excellent electronic conductivity of the C-coated Li₄Ti₅O₁₂ resulted from the presence of the highly conducting carbon coating layer and the mixed valence state of Ti³⁺ and Ti⁴⁺. Both the nanoporous morphology and highly conducting carbon coating layer in Li₄Ti₅O₁₂ particles gave rise to ultra high rate capability.