【作者】 李溪；

【导师】 白晋涛；

【作者基本信息】 西北大学 ， 光学， 2018， 硕士

【摘要】 本文基于石墨烯膜,以提高锂离子电池性能为目的,通过对钼酸镍形貌的调控、石墨烯膜厚度的设计以及三维结构的复合来提高其电化学性能,主要研究了以下三个方面:首先对钼酸镍(NiMoO4)进行了形貌上的调控,制备了钼酸镍纳米棒(NiMoO4nanorods)和钼酸镍纳米花(NiMoO4 nanoflower)。通过SEM表征发现,钼酸镍纳米棒的直径在100-250纳米之间,表面光滑。钼酸镍纳米花通过TEM表征发现纳米花以钼酸镍纳米片为基底而生长。通过对比电化学性能,钼酸镍纳米棒的循环性能要优于钼酸镍纳米花,而钼酸镍纳米花的倍率性能要略好与钼酸镍纳米棒。其次,通过真空抽滤和热处理的方法合成了三种厚度的自支撑r GO膜并对其进行了一系列表征,测试了不同厚度r GO膜的电化学性能,其中10.1微米厚的r GO膜的循环性能要优于其他两种厚度的r GO膜,而9.3微米厚的r GO膜的倍率性能要略好于其他两种厚度的r GO膜。最后,以r GO膜为基础与钼酸镍纳米棒复合,制备出了自支撑的NiMoO4/r GO复合膜,形成了三维多层堆叠的网络结构。这种结构不仅提高了离子转移和扩散的效率并且缓释了NiMoO4纳米棒在循环中的体积膨胀效应。NiMoO4纳米棒和r GO之间的协同作用使NiMoO4/r GO膜电极(无粘结剂和导电胶)比NiMoO4粉末电极展现出了更好的循环稳定性,同时提高了倍率性能。更多还原

【Abstract】 The purpose of this paper was to improve the performance of lithium ion batteries based on the graphene membrane.Through the regulation of the morphology of nickel molybdate,the design of the thickness of the graphene membrane and the composite of three-dimensional structure,the electrochemical performance of the lithium ion battery was improved.The following three aspects were mainly studied:NiMoO4 nanorods and NiMoO4 nanoflower were prepared by controlling the morphology of the nickel molybdate.NiMoO4 nanorods were with a diameter of 100-250 nm and the surface of nanorod is smooth.NiMoO4 nanoflowers were growth on the substrate of NiMoO4 nanofilm.After 100 cycles,the capacity of NiMoO4 nanorods was higher than NiMoO4 nanoflowers.And the NiMoO4 nanoflowers features better rate performance than that of the NiMoO4 nanorods.Secondly,three kinds of thickness of free-standing r GO membranes were fabricated through the method of vacuum filtration and heat treatment.The electrochemical properties of r GO membranes with different thickness were tested,the cycle performance of r GO membrane of 10.1 μm was better than the other two,and the rate performance of r GO membrane of 9.3 μm was better than the other two films.Based on r GO membrane and NiMoO4 nanorods.A free-standing and flexible NiMoO4 nanorods/r GO membrane with a three-dimensional hierarchical structure was successfully synthesized by a general approach including vacuum filtration followed by thermal reduction.NiMoO4 nanorods with about 50 ? 100 nm diameter were embedded homogenously into the 3D r GO sheets and assembled with r GO to form a membrane about 10 μm in thickness.The NiMoO4/r GO membrane could be directly evaluated as anode materials for lithium-ion batteries(LIBs)without using binder.The 3D layerstacked graphene hierarchical architecture can not only offers a continuous conducting framework for efficient diffusion and transport of ion/electron,but also accommodates the large volume expansion of NiMoO4 nanorods changes during cycling.Moreover,our results show that NiMoO4/r GO membrane exhibited excellent electrochemical performance with a high reversible capacity of 945 m Ah g-1 at a current density of 0.25 A g-1 as anode materials in LIBs.更多还原