三维石墨烯纳米球的制备及其在锂离子电池中的应用

Preparation and Application of Three-dimensional Graphene Nanospheres in Lithium Ion Battery

采用直流电弧放电法制备出一种三维石墨烯纳米球材料。采用扫描电镜(SEM)、透射电镜(TEM)、拉曼光谱和X射线衍射光谱(XRD)等测试方法对三维石墨烯纳米球的形貌和结构进行了表征和研究。通过交流阻抗(EIS)、恒流充放电和循环稳定性测试等电化学测试手段来研究三维石墨烯纳米球作为锂离子电池负极材料的电化学性能。结果表明,在电流密度为0.05 A/g下,三维石墨烯纳米球作为锂离子电池负极材料的首次放电容量为485.9 m Ah/g,高于炭黑作负极的放电容量(401 m Ah/g);当电流密度为1 A/g时,三维石墨烯纳米球负极材料仍然具有185.4 m Ah/g的放电容量。在电流密度分别为0.5 A/g和2.5 A/g下,充放电循环100次以后,三维石墨烯纳米球的比容量几乎没有衰减,这表明三维石墨烯纳米球作为锂离子电池的负极材料比炭黑具有更大的容量,同时具有优异的循环稳定性。

Three-dimensional graphene nanospheres were prepared by direct-current arc discharge method. The mi- crostructure and morphology of the graphene nanospheres were characterized by transmission electron microscope （TEM）, scanning electron microscope （SEM）, Raman spectrum and X-ray diffraction （XRD） pattern. The electro- chemical properties of the three-dimensional graphene nanospheres as the anode materials of lithium ion battery were studied by alternating current impedance and constant current charge-discharge cycle performance. The results show that, at current density of 0.05 A/g, the graphene nanospheres as the anode materials have a high first discharge capac- ity of 485.9 mAh/g, which is better than has the carbon black （401 mAh/g）. When the current density increases to 1 A/g, the three-dimensional nanospheres can still achieve a capacity of 185.4 mAh/g. The three-dimensional nanospheres have little capacity decay after 100 cycles at current density of 0.5 A/g and 2.5 A/g. The results show that the three-dimensional graphene nanospheres have a higher capacity than carbon black as the anode for lithium ion battery, and they have excellent cycling stability, too.