球形“花”状结构MoS2/石墨烯锂离子电池负极材料及其电化学行为

Synthesis and electrochemical performance of a spherical flower-like MoS2/graphene anode material for lithium ion batteries

  • 摘要: 以氧化石墨烯、钼酸钠、硫脲为原料,采用水热法在240℃原位合成MoS2/石墨烯纳米复合材料,并考察了其作为锂离子电池负极材料的电化学性能。结果表明:由片层纳米结构自组装形成球形“花”状结构的MoS2分散于石墨烯表面;MoS2/石墨烯负极材料,在100 mA/g电流密度下100次循环后,放电容量仍达735.2 mAh/g,并具有良好的大电流倍率性能(375 mAh/g,1 000 mA/g)。该结果应归因于:合成的MoS2为较薄的片层结构,减小了离子、电子的扩散或迁移路径;片层结构的MoS2自组装成球形“花”状,构筑了丰富的中孔,有利于离子的扩散和存储,也能抑制材料在充放电过程中的体积膨胀;石墨烯良好的导电性及高比表面积,能有效提高MoS2的充放电速度。

     

    Abstract: A MoS2/graphene composite was synthesized at 240℃ by a hydrothermal method using graphene oxide, Na2MoO4 and CS(NH2)2 as the raw materials. Results indicate that the spherical flower-like MoS2 structure was self-assembled by thin MoS2 micrometer size layers and dispersed uniformly on the surface of graphene. The MoS2/graphene composite as an anode material retains a capacity of 735.2 mAh/g after 100 cycles under a current density of 100 mA/g and has a good rate performance (490.3 mAh/g at 400 mA/g and 411.9 mAh/g at 800 mA/g). The excellent electrochemical performance of the composite is attributed to its special structure. The thin MoS2 layers shorten the diffusion and transport paths for Li+ ions and electrons. The abundant mesopores are beneficial for ion diffusion and act as a buffer to inhibit volume changes during charge-discharge. Graphene increases the charge-discharge rate of MoS2 effectively owing to its high conductivity and high surface area.

     

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