Lithium titanate hybridized with trace amount of graphene used as an anode for a high rate lithium ion battery

Abstract

A novel Li4Ti5O12 (LTO) electrode with a hierarchical carbon-based conducting network has been developed for high rate lithium ion battery. The unique network is constructed by graphene sheets (GS) that are not only dispersed among (inter-) but also inside (intra-) LTO particles, together with a thin carbon layer wrapping around the LTO particles. The intraparticle GS promotes the electron transfer inside LTO particles while the interparticle GS together with carbon coating bridges the particles guaranteeing fast electron transfer among LTO particles, which construct a highway throughout the whole electrode sheet. Quantitatively, only a trace amount of GS (∼ 0.4 wt%) synergistic with carbon coating (∼0.8 wt%) contributes to a more effective conducting network in the produced LTO electrode and as a result much better performance as compared to the LTO case with similar carbon coating but free of GS. Due to the effectiveness of the conducting network, even with a tap density as high as ∼1.0gcm−3, the novel LTO possesses both excellent rate performance and cycling behaviors. The capacity of 123.5mA h g−1 is obtained at a charge/discharge rate as high as 30C and a very high capacity of 144.8 mAh g−1 is maintained even after 100 cycles at 10C. Due to such a low fraction of carbon and a high tape density, the novel LTO electrode has a great practical application value in both the power and energy storage lithium ion batteries.