Nanosized Li4Ti5O12/graphene hybrid materials with low polarization for high rate lithium ion batteries

We report a simple strategy to prepare a hybrid of lithium titanate (Li4Ti5O12, LTO) nanoparticles well-dispersed on electrical conductive graphene nanosheets as an anode material for high rate lithium ion batteries. Lithium ion transport is facilitated by making pure phase Li4Ti5O12 particles in a nanosize to shorten the ion transport path. Electron transport is improved by forming a conductive graphene network throughout the insulating Li4Ti5O12 nanoparticles. The charge transfer resistance at the particle/electrolyte interface is reduced from 53.9 Omega to 36.2 Omega and the peak currents measured by a cyclic voltammogram are increased at each scan rate. The difference between charge and discharge plateau potentials becomes much smaller at all discharge rates because of lowered polarization. With 5 wt.% graphene, the hybrid materials deliver a specific capacity of 122 mAh g(-1) even at a very high charge/discharge rate of 30C and exhibit an excellent cycling performance, with the first discharge capacity of 132.2 mAh g(-1) and less than 6% discharge capacity loss over 300 cycles at 20C. The outstanding electrochemical performance and acceptable initial columbic efficiency of the nano-Li4Ti5O12/graphene hybrid with 5 wt.% graphene make it a promising anode material for high rate lithium ion batteries. (C) 2011 Elsevier B.V. All rights reserved.