低价钒氧化物复合材料的制备及其电化学性能

发布时间：2018-03-09 12:22

本文选题：豆荚结构V2O3@C　切入点：VO2/Graphene　出处：《武汉科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：锂离子电池和超级电容器是两类重要的储能器件。锂离子电池具有高的能量密度和相对低的功率密度，而超级电容器具有高的功率密度、长的循环寿命和相对低的能量密度。因此，如何提高锂离子电池的功率密度和超级电容器的能量密度是这两类储能器件的研究焦点。钒氧化物具有独特的层状结构有利于离子的嵌入和脱出，具有较高的理论容量和较宽的电势窗范围，是一类理想的储能电极材料。然而钒氧化物的导电性较差，通过与碳材料的复合提高材料的导电性能获得高的功率密度，构建特殊的复合结构缓解嵌锂时产生的体积膨胀提高材料的循环稳定性。具体研究内容如下： 1、以五氧化二钒为钒源通过水热法获得尺寸均匀、长度100μm以上的超长有序V3O7H2O纳米线，再通过水热法在纳米线表面包覆一层薄碳层，形成了V3O7H2O@C纳米结构，然后经过不同温度退火获得豆荚结构的V2O3@C，碳层具有极高的导电率可为电荷的快速传输提供便捷通道，提高材料的倍率性能；内核豆荚结构可以确保电解液与V2O3的有效接触，缓解锂离子在嵌入和脱出过程中体积发生的变化，有利于复合电极比容量和循环稳定性的提高。超长纳米线可以直接成膜作为电极材料，不需要添加没有活性的粘结剂和额外的导电剂，是理想的柔性电极基体。 2、以五氧化二钒为钒源，取一定量的GO溶液混合均匀，，通过水热法直接制备了VO2纳米带和石墨烯复合材料（VO2/graphene）。VO2具有独特的层状结构可以提供额外的插层电容，提高材料的能量密度；VO2/graphene中的石墨烯片层能够提供一个导电网络，提高材料的倍率性能；石墨烯层包覆VO2纳米带后，能避免VO2在充放电过程中所产生的电化学溶解现象，极大的改善材料的循环稳定性。
[Abstract]:Lithium ion batteries and supercapacitors are two important energy storage devices. Lithium ion batteries have high energy density and relatively low power density, while supercapacitors have high power density. Long cycle life and relatively low energy density. How to improve the power density of lithium-ion batteries and the energy density of supercapacitors is the research focus of these two kinds of energy storage devices. Because of its high theoretical capacity and wide range of potential window, it is an ideal material for energy storage electrode. However, vanadium oxide has poor conductivity and high power density can be obtained by improving the conductivity of the material by compounding with carbon material. A special composite structure is constructed to alleviate the volume expansion produced by lithium intercalation to improve the cyclic stability of the material. The specific contents of the study are as follows:. 1. Ultralong ordered V _ 3O _ 7H _ 2O nanowires were obtained by hydrothermal method using vanadium pentoxide as a source of vanadium. The ultralong ordered V _ 3O _ 7H _ 2O nanowires were obtained by hydrothermal method, and then a thin carbon layer was coated on the surface of the nanowires by hydrothermal method to form V _ 3O _ 7H _ 2O _ C nanostructures. Then after annealing at different temperatures, V _ 2O _ 3 @ C with pod structure was obtained. The carbon layer with extremely high conductivity can provide a convenient channel for fast charge transfer and improve the performance of the material, and the core pod structure can ensure the effective contact between electrolyte and V _ 2O _ 3. It is helpful to improve the specific capacity and cycle stability of the composite electrode by alleviating the volume change of lithium ion in the process of intercalation and stripping. The ultra-long nanowires can be used as electrode materials directly. It is an ideal flexible electrode matrix without adding inactive binder and extra conductive agent. 2. Using vanadium pentoxide as vanadium source, a certain amount of go solution was mixed uniformly, and VO2 nanobelts and graphene composites VO _ 2 / V _ 2 / V _ 2 / V _ 2 / V _ 2 / V _ 2 / V _ 2 / V _ 2 composites were prepared directly by hydrothermal method to provide additional intercalation capacitors. The graphene layer in VO2 / graphene can provide a conductive network and improve the performance of the material, and the graphene coating can avoid the electrochemical dissolution of VO2 during charge and discharge. Greatly improve the cyclic stability of materials.
【学位授予单位】：武汉科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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