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.