Enhancing Lithium Storage Performances of the Li₄Ti₅O₁₂Anode by Introducing the CuV₂O₆Phase

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 <i>in situ</i> X-ray diffraction (XRD) analysis. The acquired data confirms that <i>in situ</i> 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.