石墨烯/钛酸锂复合材料制备研究

Synthesis and Characterization of Li_4Ti_5O_(12)/Graphene Composite as Anode Material with Enhanced Electrochemical Performance

采用易于工业化的固相法合成Li4Ti5O12以及Hummers法制备氧化石墨烯,并以N2H4·H2O为还原剂制备石墨烯材料,在此基础上高能球磨合成Li4Ti5O12/Grephene复合材料。借助X射线衍射、扫描电镜、能谱分析对合成的样品进行结构和形貌表征,并采用恒流充放电、交流阻抗和循环伏安等测试方法检测其电化学性能。充放电结果表明:复合前后材料形貌不发生变化,石墨烯均匀地附着在Li4Ti5O12表面。由于石墨烯具有良好的导电性,材料的倍率性能得到大幅提高。在充放电倍率为20 C时,复合材料的比容量约为120.2 m Ah·g-1,而纯相钛酸锂的比容量只有61mAh·g-1。

Li4Ti5O12 was prepared by solid-state reaction, graphene oxide was synthesized by the Hummers＇ method and then it was reduced by N2H4·H2O to obtain graphene. High-energy ball milling was adopted to prepare Li4Ti5O12/graphene composite. The crystalline structure, morphology, composition and electrochemical properties of the composite were characterized by XRD, SEM, TEM and half cell charge-discharge. Among the as-synthesised composites, Li4Ti5O12 particles uniformly clung to the graphene sheets. Because graphene has good electrical conductivity, the composite presents excellent rate performance and high cyclic stability. The specific capacity of composites is as high as 120.2 m Ah·g-1 when they cycled at 20 C, whereas that of the pristine Li4Ti5O12 particles is only 57.6 m Ah·g-1. The excellent electrochemical performance is attributed to the decrease in the charge-transfer resistance.