摘要
以Ge O2和氧化石墨烯（GO）为前驱体,用水热法制备纳米Ge/石墨烯（Ge/GNs）复合材料.扫描电镜（SEM）和透射电镜（TEM）得到在复合材料中,石墨烯包覆着锗纳米粒子,这与纯相Ge材料相比,会缓解锂嵌入Ge内部产生的体积膨胀.并且得到纳米Ge粒子粒径约为40 nm左右.第一次充放电容量分别是1385 m Ah·g-1和1982m Ah·g-1,库伦效率为70%.50圈充放电循环之后,容量保持在954 m Ah·g-1,容量的保持率为69%,纳米Ge/GNs复合材料高倍率循环后,在初始（0.1 C）电流密度下仍能保持1102 m Ah·g-1的容量.而在2 C倍率大电流下,容量略有衰减,保持911 m Ah·g-1的容量.纳米Ge/GNs复合材料在高电流密度下充放电性能显示出较高的稳定性.实验证明,由于加入石墨烯,复合材料的导电性和循环稳定性得到增强,库伦效率也随之提高.
Germanium/graphene nanosheets（Ge/GNs） composite was synthesized through a hydrothermal method using Ge O2 and graphene oxide as the precursors. It was evident that graphene takes an important role in the electrochemical properties of the composite by comparing with that pure Ge nanoparticles. Scanning electron microscopy indicated that the Ge nanoparticles are encapsulated inside the GNs, which limits and buffers the volume change of the Ge during lithium alloying/dealloying. The experimental results implied that the size of Ge/GNs nanoparticles is about 40 nm, which delivers a first charge and discharge capacities of 1982 and 1385 m Ah·g-1, giving a Coulombic efficiency of about 70%. After 50 cycles, the capacity is consist at 954 m Ah·g-1, and the capacity retention is 69%. The composite electrode also showed good rate performance, showing 911 m Ah·g-1at a scan rate of 2C. The excellent properties of the composite could be partially contributed to the presence of GNs which reduces the volume stress in Ge anode during Li insertion/extraction and enhances the electronic conductivity of the composite.
出处
《闽南师范大学学报：自然科学版》
2015年第4期64-70,共7页
Journal of ZhangZhou Teachers College（Natural Science）
关键词
GeO2
石墨烯
锂离子电池
负极材料
水热法
germanium dioxide
graphene
lithium-ion battery
anode materials
hydrothermal method
