氧化石墨制备温度对石墨烯结构及其锂离子电池性能的影响

Effects of preparation temperature of graphite oxide on the structure of graphite and electrochemical properties of graphene-based lithium-ion batteries

采用改进的Hummers法,以石墨粉为原料制备氧化石墨,然后使用微波还原法制备石墨烯,最后以石墨烯作为负极材料组装锂离子电池.系统的研究了高温氧化阶段中温度对氧化石墨的氧化程度、石墨烯的还原程度和比表面积以及锂离子电池性能的影响.利用场发射扫描电镜(FESEM)、X射线光电子能谱(XPS)、X射线衍射仪(XRD)、BET测量仪对氧化石墨和石墨烯的微观结构及比表面积等进行测试和表征.XRD,XPS及电化学测试的结果显示当高温阶段氧化温度为90℃时,氧化石墨的氧化程度最高,相应的石墨烯也具有最高的还原程度和最大的比表面积423.2 m^2/g,同时石墨烯锂离子电池也具有更好的性能:首次放电比容量为1555.5 mAh/g,充电容量为1024.6 mAh/g,其循环放电比容量达到600 mAh/g.

Graphite oxide is synthesized from graphite powder by a modified Hummers method,and the oxidation temperature is controlled in high-temperature oxidation process.By treating graphite oxide powders in a commercial microwave oven,graphene materials can be readily obtained.The morphologies,microstructures,specific surface areas and other features of the graphene and graphite oxide are characterized by FESEM,XPS,XRD and BET.Electrochemical performances of the lithium-ion batteries based on graphene anodes are investigated.The results show that graphene obtained at the oxidation temperature of 90℃in high-temperature oxidation process actually displays the most remarkable electrochemical performances,that is,the first discharge specific volume and charge capacity of graphene are as high as 1555.5 mAh/g and 1024.6 mAh/g,and after 30 cycles graphene still possess as high as a discharge capacity of 600 mAh/g.