Enhancing Lithium Storage Performances of the Li4Ti5O12 Anode by Introducing the CuV2O6 Phase.

Abstract

The low electronic conductivity of spinel-structured Li4Ti5O12 could be improved by introducing CuV2O6. Herein, several Li4Ti5O12/CuV2O6 composites with different CuV2O6 contents have been successfully prepared by a facile liquid-phase dispersion technique. The amount of CuV2O6 in composites is shown to affect the particle size and electrochemical performances of Li4Ti5O12. The Li4Ti5O12/CuV2O6 composite prepared with a 5 wt % CuV2O6 content (referred to as 5 wt % Li4Ti5O12/CuV2O6) exhibits the best electrochemical performances among all the Li4Ti5O12/CuV2O6 composites. The initial discharge/charge capacities of the 5 wt % Li4Ti5O12/CuV2O6 composite reach 241.1/199.8 mAh g-1 and retain at 136.8/135.7 mAh g-1 over 500 cycles at 30 mA g-1 between 1.0 and 3.0 V. In addition, initial discharge/charge capacities of the 5 wt % Li4Ti5O12/CuV2O6 composite amount to 129.8/90.5 mAh g-1 even at 1200 mA g-1 with maintained discharge/charge capacities of 71.1/71.1 mAh g-1 over 2500 cycles, which are superior to the pristine Li4Ti5O12 in all cases. The detailed electrode kinetic analysis reveals that the introduction of the CuV2O6 phase can enhance the lithium-ion transferring rate and cycling stability of Li4Ti5O12. The enhanced lithium-storage mechanism of the 5 wt % Li4Ti5O12/CuV2O6 composite is clarified by in situ X-ray diffraction (XRD) analysis. The acquired data confirms that in situ formation of small amounts of metallic Cu during discharge/charge processes highly enhance the electronic conductivity and decreases the charge-transfer resistance of Li4Ti5O12. In sum, the as-obtained 5 wt % Li4Ti5O12/CuV2O6 composite has potential for future construction of high-rate and long-lifespan anode materials for Li-ion batteries. The work also provides an innovative route to improve electrochemical performances of Li4Ti5O12.