Sn量子点/石墨烯复合材料的合成及储锂性能

Synthesis and lithium storage properties of Sn quantum dots/graphene composite

  • 摘要: Sn基材料是目前高容量锂离子电池电极材料研究的热点,但循环性能较差阻碍了其大规模应用。以氧化石墨烯为载体,通过化学还原法在载体表面成功均匀负载<10 nm的Sn量子点,合成Sn量子点/石墨烯(SnQds/rGO)复合电极材料。结果表明,Sn质量分数为90wt%的SnQds/rGO复合材料具有良好的综合电化学性能,首次放电容量和库伦效率分别为939 mAh/g和66.6%,经过200次循环后容量可达621 mAh/g,容量保持率为66.1%。小尺寸的Sn量子点与石墨烯复合能够增强电极材料的结构稳定性和降低阻抗,改善电极材料的循环性能和倍率性能,但会导致首次库伦效率有所降低。

     

    Abstract: The Sn-based materials have been a focus as promising high-capacity electrode materials of lithium-ion battery. However, its poor cycling performance has severely restricted the large-scale practical applications. The Sn quantum dot/graphene (SnQds/rGO) composite electrode material was synthesized by chemical reduction method, using graphene oxide as the carrier. The Sn quantum dots with <10 nm were uniformly loaded on the surface of graphene. The experimental results show that the SnQds/rGO composite with Sn mass fraction of 90wt% has good comprehensive electrochemical performance. The first discharge capacity and Coulomb efficiency of the SnQds/rGO composite are 939 mAh/g and 66.6%, respectively. It’s discapacity can reach 621 mAh/g after 200 cycles and the capacity retention rate is 66.1%. The structure stability of SnQds/rGO composite is improve, meanwhile its impedance reduce, owing to the commposite of small size Sn quantum dots and graphenethe. As a result, the cycle performance and rate performance of the SnQds/rGO composite have been significantly improved. However, the initial Coulomb efficiency of SnQds/rGO composite decreases.

     

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