钒酸铜材料的制备及电化学性能研究

发布时间：2018-05-25 19:26

  本文选题：锂离子电池 + Cu_2V_2O_7　； 参考：《陕西科技大学》2017年硕士论文

【摘要】：众多清洁能源的推广应用对新一代储能系统提出更高的要求。锂离子电池凭借其众多优势,成为大型储能系统的首选设备之一。目前制约锂离子电池发展的关键因素就是其电极材料容量较低,无法满足现实需求。具有层状结构和多步还原特性的钒酸铜材料,在诸多领域均显示出优异的性能,具有广泛的应用前景。但目前对其电化学性能的研究还处于初步阶段。本论文通过不同方法,通过调控工艺参数制备出不同物相及形貌的钒酸铜材料,采用X射线衍射、扫描电镜等表征方法以及恒流充放电设备、循环伏安曲线和阻抗测试等研究了制备工艺对材料组成、结构和电化学性能的影响。采用固相法制备出不同物相的钒酸铜材料,探究不同煅烧温度,保温时间及原料配比对产物的物相、形貌及电化学性能的影响。发现提高煅烧温度,产物的结晶性和粒径尺寸逐渐增加,产物物相从α相变为β相。产物形貌也发生了从不规则颗粒状逐渐生长为珊瑚状,再到不规则块状的变化。当铜钒物质的量之比为1:1,600 ℃保温2h,可制备出珊瑚状α-Cu2V2O7材料。在50mA·g-1条件下,其可逆容量为370mAh·g-1。以氧化亚铜代替氧化铜作为铜源,可大幅度缩短反应所需的时间,降低反应温度。以氧化亚铜为铜源及模板,采用水浴法制备出三维花状Cu3V2O7(OH)2·2H2O材料。通过调节温度及pH,可实现对产物形貌和物相的控制。发现相对于纯相 Cu3V2O7(OH)2·2H2O,Cu3V2O7(OH)2·2H2O/Cu2O复合材料具有更优异的电化学性能。其中,pH为7.41,在70℃水浴反应5 h制得的花状样品,在100 mA·g-1电流密度下,其首次放电比容量为941.3 mAh·g-1,100圈循环后容量为414.7 mAh g-1。采用水热法结合后续热处理,在较低的温度下合成出具有介孔结构的球状Cu2V2O7/rGO复合材料。研究了反应温度、时间以及还原氧化石墨烯的加入量对产物物相及性能的影响。60℃下反应20 h,复合0.6%还原氧化石墨烯,经热处理所得材料具有较好的电化学性能,在100mA·g-1电流密度下,其首次放电比容量为1245 mAh·g-1,100圈循环之后,容量可保持在 900 mAh·g-1。在 100、200、500、1000、2000、5000 mA·g-1 的电流密度下比容量分别为890、817、690、524、328、170 mAh·g-1,其性能明显优于纯相Cu2V207。适量还原氧化石墨烯的加入,可提升材料的电化学性能,其与Cu2V207之间具有协同储能效应。
[Abstract]:The popularization and application of many clean energy sources put forward higher requirements for the new generation energy storage system. Lithium ion battery has become one of the first choice equipment of large energy storage system with its many advantages. The key factor restricting the development of lithium-ion battery is that its electrode material capacity is low, which can not meet the actual demand. Copper vanadate with layered structure and multi-step reduction has shown excellent properties in many fields and has a wide application prospect. However, the study of its electrochemical performance is still in its preliminary stage. In this paper, copper vanadate materials with different phases and morphologies were prepared by adjusting the process parameters by different methods. The materials were characterized by X-ray diffraction, scanning electron microscopy and constant current charging and discharging equipment. The effects of preparation process on the composition, structure and electrochemical properties of the materials were investigated by cyclic voltammetry and impedance measurements. Copper vanadate with different phases was prepared by solid phase method. The effects of different calcination temperature, holding time and ratio of raw materials on the phase, morphology and electrochemical properties of the products were investigated. It was found that the crystallinity and particle size of the product increased gradually with the increase of calcination temperature, and the phase transition from 伪 to 尾 phase was observed. The morphology of the product also changed from irregular granular to coral and then irregular block. Coral-like 伪 -Cu _ 2V _ 2O _ 7 can be prepared when the ratio of copper and vanadium is 1: 1600 鈩，

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