石墨烯负载镍基多金属氧酸盐负极材料及其电化学性能

Graphene-supported Ni-based polyoxometalate anode material and its electrochemical performance

  • 摘要: 能源危机是目前全球关注的重要问题。锂离子电池(LIB)由于其能量密度高,循环寿命好,环境友好等,已成为当前最热门的新能源技术。尽管商用的碳负极能有效降低锂枝晶的生成,但是其在储能密度方面仍然达不到人们日益增长的需求。因此,设计合成新型的锂离子电池电极材料是突破高能锂离子电池瓶颈的关键问题之一。本文作者成功合成了一种石墨烯负载多金属氧酸盐-有机骨架材料(Ni-POMs),并且将该材料用于锂离子电池负极。扫描电镜(SEM)分析显示Ni-POMs材料具有规则的六棱柱形状,X-射线衍射(XRD)测试结果显示实验样品的衍射峰与计算模拟衍射峰一致。石墨烯负载后样品的形貌出现部分破坏,但仍可以观察到六棱柱形状。在100 mA/g电流密度下,经过50次循环后Ni-POMs材料的放电比容量可达到717 mAh/g。在800 mA/g的电流密度下,循环500次后仍能保持82.2%的容量保持率。经过石墨烯负载后,Ni-POMs@GO材料的循环性能和倍率性能进一步得到提升。Ni-POMs@GO电极的材料循环稳定性主要得益于其独特的多孔特性和高化学稳定性,石墨烯负载后为材料提供了电子传输通道,进一步提升了其电化学性能。

     

    Abstract: The energy crisis is currently an important issue of global concern. Lithium-ion battery (LIB) has become the most popular new energy technology due to its high energy density, good cycle life, and environmental friendliness. Although the commercial carbon anode can effectively reduce the formation of lithium dendrites, it still fails to meet the increasing demand for energy storage density. Therefore, designing and synthesizing new electrode materials for LIB is one of the key issues to break the bottleneck of high-energy LIB. In this work, a graphene-supported polyoxometalate-organic framework material (Ni-POMs) was successfully synthesized and used for the anode of LIB. Scanning electron microscopy (SEM) analysis showed that Ni-POMs material has a regular hexagonal prism shape, and X-ray diffraction (XRD) test results showed that the diffraction peak of the experimental samples were consistent with computer simulated one. After the graphene was loaded, the morphology of its sample was partially damaged, but the hexagonal prism shape could still be observed. At a current density of 100 mA/g, the specific discharge capacity of Ni-POMs could reach 717 mAh/g after 50 cycles. At a current density of 800 mA/g, a capacity retention rate of 82.2% could be maintained after 500 cycles. After graphene loaded, the cycle performance and rate performance of Ni-POMs@GO materials further improved. The material cycle stability of Ni-POMs@GO electrode mainly attributes to its unique porous characteristics and high chemical stability. Loaded graphene provides an electron transport channel for the materials, which further improves its electrochemical performance.

     

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