超长储锂寿命SnO2量子点修饰石墨烯的制备

Facilely synthesis of SnO2 dots decorated reduced graphene oxide with ultra-long lithium storage life

  • 摘要: 在锂离子电池中,商用阳极石墨的利用率已经接近其理论容量的极限(372 mAh·g−1),一些金属基复合材料因其更高的储锂能力和更稳定的循环性能而受到广泛关注。本文采用改性的胶体聚沉法及随后空气煅烧的工艺制备了SnO2量子点修饰的还原氧化石墨烯(rGO/SnO2)。作为锂离子电池阳极,rGO/SnO2具有优异的储锂性能。在1和2 A·g−1电流密度下,rGO/SnO2-70电极在1000次循环后依然可以分别保留584和378 mAh·g−1的可逆放电比容量。这主要是因为SnO2量子点“壳”不仅可以提供大量的活性位点,缩短Li+脱/嵌过程中的传输路径长度,并可以阻止充放电过程中rGO纳米片的堆叠,从而实现了SnO2较高的利用率;rGO“核”能够实现电子的快速传输,缓冲SnO2的体积变化,从而使rGO/SnO2具有良好的循环稳定性。本研究可以为高倍率、超长循环寿命的复合阳极材料的设计提供参考。

     

    Abstract: In lithium-ion batteries (LIBs), commercial anodic graphite has reached its limit of theoretical capacity and some metal-based materials are drawing substantial attention due to their higher Li+ storage ability and better cyclic performance. In this paper, SnO2 dots are facilely bridged chemically with reduced graphene oxide (rGO) nanosheets via a modified colloidal coagulation synthesis and a following calculation process in air. As anodes for LIBs, the obtained rGO/SnO2 shows excellent electrochemical performances. At 1 and 2 A·g−1, the rGO/SnO2-70 electrode delivers stable reversible capacities of 584 and 378 mAh·g−1 after 1000 cycles, respectively. It is believed that SnO2 dots shorten the Li+ transport path length and support more electroactive sites for Li+ alloying/de-alloying reactions, leading to high reversible capacities. Meanwhile, the bridged chemically SnO2 dots could prevent the re-stacking of rGO nanosheets. On the other hand, the conductive underneath core-rGO enables an ultrafast electron transport and accommodates the volume changes of the SnO2 dots, leading to a good cyclic stability. This study provides a reference for the novel anodic carbonaceous materials with high capacity at high current density and ultra-long cyclic life.

     

/

返回文章
返回