VO_2/rGO复合材料的制备及作为高容量锂离子电池负极的研究

Synthesis and electrochemical properties of VO_2/rGO composite for high-performance anode materials for Li-ion batteries

采用简易的一步水热法实现了VO_2和rGO的有效复合,通过XRD、SEM、Raman等手段对复合材料的结构和形貌进行了表征,评估了该材料作为锂离子电池负极的电化学性能。结果显示,VO_2为片状形貌,氧化石墨烯在水热反应中被还原,与VO_2片形成了良好的复合结构。电化学数据显示,在100 mA/g电流密度下,VO_2/rGO复合材料可逆容量高达621.8mAh/g,远高于石墨的理论容量(372mAh/g)。在300mA/g电流密度下,该材料在100次循环后容量保持在384mAh/g。更重要的是,在2 000mA/g电流密度下,300次循环后容量仍维持在256mAh/g,容量保持率接近100%。基于rGO良好的导电性能以及VO_2与rGO的协同作用,制备的VO_2/rGO复合材料体现了较高的可逆比容量和良好的倍率性能及循环稳定性能,是一种具有前景的锂离子电池负极材料。

In this work, VO2/rGO composite was successfully prepared by a simple one-step hydrothermal method. The structure and morphology of the as-prepared composites were characterized by XRD, SEM and Raman measurements. Its electrochemical performance as anode for lithium ion batteries was also evaluated. The results show that VO2 was flak and well anchored together with graphene oxide reduced during the hydrothermal reaction. When used as anode for lithium ion battery, this composite exhibited a high capacity of 621.8 mAh/g at 100 mA/g, which is much higher than the theory capacity of graphite （372 mAh/g）. At 300 mA/g, it maintained a capacity of 384mAh/g after 100 cycles. Even at a higher current density of 2 000 mA/g, the discharge capacity was still retained 256 mAh/g after 300 cycles with capacity retention of almost 100%. Owing to the excellent conductivity of rGO and the synergistic effect between VO2 and rGO, the VO2/rGO composite demonstrated high reversible capacity, good rate performance and excellent cycling stability. It was a promising anode material for lithium ion battery.