Enhanced performance of spherical natural graphite coated by Li4Ti5O12 as anode for lithium-ion batteries

The natural graphite (NG) is coated with Li4Ti5O12 (LTO) and the composite shows a markedly enhanced rate performance due to the decrease of charge transfer resistance after LTO coating. The specific capacity of the NG charge-discharged at 2 C is increased by 60.3% (128.7 vs. 80.3 mAh g(-1)) by coating it with 1 wt.% of Li4Ti5O12 (LTO). The comparison of the NG and that coated with 1 wt.% LTO at 0.1 C shows that the initial reversible capacity is increased from 318.1 mAh g(-1) to 357.5 mAh g(-1) after coating, while the total irreversible capacity loss after 50 cycles is decreased from 122.8 mAh g(-1), to 103.9 mAh g(-1). The composite improves the energy and power densities, safety, cycle life and lowers the price of the lithium-ion battery while avoiding the gas-swelling of full battery caused by Ti4+ because the final coating material is the lithiated LTO (Li7Ti5O12 or Li9Ti5O12). (C) 2012 Elsevier B.V. All rights reserved.