【作者】 王宁；

【导师】 李明； 杭弢；

【作者基本信息】 上海交通大学 ， 材料科学与工程， 2016， 博士

【摘要】 能源、信息和材料是近代社会得以繁荣发展的三大支柱。其中,能源是社会发展的基石,在日益增大的全球变暖、空气质量恶化等环境压力下,可持续能源的生产、存储和消费是当今世界所面临的重大挑战。目前的核心目标包括两个方面,一方面如何构建可持续的新型能源,另一方面是如何有效的存储和释放能量以满足实际应用的需求。材料是各个领域的基础,材料的发展推动着各个领域的发展。表面微纳米结构材料由于较大的比表面积和特殊的电、磁、光、热的等性能,受到广大科研者的青睐。本文以表面微纳米针/锥材料为基础,实现了对其结构的灵活控制,研究了其生长机理,并探索了其在锂电池负极材料和催化制氢方面的应用,主要研究内容和取得的进展如下:1.将铜微/纳米锥阵列作为电沉积锡的基底,得到了一种基于微/纳米锥阵列的新型锡基负极材料,并以该锡基负极材料为基础,研究了镀层厚度、基底铜针尺寸、热处理对电池性能的影响。结果表明该三维集流体对锡体积变化有一定的缓冲作用,但效果不如硅明显;长时间热处理也有助于循环性能的提升,比容量随热处理时间增加而呈现先上升后下降的趋势。2.通过一步电沉积的方法制备了铜纳米锥阵列材料,作为锂离子电池负极的集流体,磁控溅射三种不同时间的硅膜之后进行了电化学测试。沉积硅层50min（50CuSi）和70min（70CuSi）电极在1.5C都展示了2000个循环的优异的循环性能,这两种电极的容量保持率分别为78.4%、69.6%。然而,沉积硅层90min（90CuSi）电极的循环性能由于没有足够的缓冲体积变化的空间而衰减的比较快。三种电极中,50CuSi电极显示了最好的倍率性能,25 C的大电流下,容量为916 mA h g^-1。3.从晶体学的角度研究了化学镀铜纳米针阵列材料的生长机制,通过改变沉积时间和结晶调整剂的浓度可以改变纳米针的高度和密度。铜纳米针由于较大的长径比从而具有更大的比表面积,作为锂离子电池负极集流体的时候,可以承载更多的活性物质。沉积硅层30min（30NNAS）的电极在1.5C的电流下1950个循环后放电容量为1141 mA h g^-1。沉积硅层60min（60NNAS）的电极在2.5C的电流下1000个循环后放电容量为490mA h g^-1。4.本文通过电镀的方法,经过大量的研究探索成功地制备了一系列Ni-Co合金锥阵列结构,填补了无模板法电化学制备合金锥方面的空白。借助于TEM、SEM、XRD等手段,研究了合金锥的生长机理及演变规律。结果表明,通过改变生长时间、温度、合金组分及结晶调整剂浓度等条件可以有效地控制合金锥结构的尺寸。借助于TEM还观察到高钴含量的合金锥中有大量的孪晶存在,主要是因为钴的加入使镀层的层错能剧烈降低。5.将上述所得到的合金纳米锥电镀到铜微米锥基底上,成功地制备出微纳米分级结构,比表面积进一步增大;镍元素和钴元素还具有协同作用,此分级结构用于催化析氢领域,交换电流密度是平面镍电极的6.7-21.9倍。更多还原

【Abstract】 Energy,materials and information are the three reasons for the prosperity and development of modern society.Among them,the energy is the cornerstone of social development.Under the pressure of increasing global warming and gradually air quality deterioration,the research and development of green and renewable energy is a major challenge facing the world today.Material is the foundation of various fields,and the development of materials promotes the development of various fields.The micro-nano structured materials have attracted considerable attention recently for their high specific area and prospects in magnetic,electronic,and electrochemical devices applications.Based on the micro-nanoneedle/cone structured materials,we realized the flexible control of the structure,researched the growth mechanism,and explored its application in hydrogen evolution reaction and lithium ion battery（LIB）anode material.The main research contents and progress are as follows:1.The micro/nanocone arrays are successfully introduced as the current collector of the electrodeposited tin.Based on the micro/nanocone arrays supported anode materials,we researched the influence of several factors on the battery performance,i.e.the thickness of electrodeposition layer,the size of substrate microcone,the time of heat treatment.Results show that 3D current collector can buffer the volume change of tin,but not obviously;long time heat treatment also help to improve the cycle performance,and the capacity increased firstly and then decreased.2.Cu nanocone-array is prepared by one-step electrodeposition as current collector of LIB anode.After magnetron sputtering Si with different time,the electrochemical performance of the NNAS structured electrodes were evaluated in a three-electrode cell.50CuSi and 70CuSi electrodes shows excellent cycle performance of 2000 cycles at 1.5 C and the discharge capacity of the two electrodes are 78.4%,69.6%,respectively.However,the cycle performance of 90CuSi electrode fades quickly because of no enough space to buffer volume change.Among the three electrodes,50CuSi electrode shows the best rate performance,with discharge capacity of 916 mA g h^-1 at25 C.3.The growth mechanism of electroless deposited Cu nanoneedle-array is studied from the perspective of crystallography.The height and density of the nanoneedle are controllable by changing the deposition time and the concentration of the crystallization agent.Cu nanoneedle can load more active material of silicon as current collector in lithium ion battery,due to the bigger specific surface area.After silicon deposition,30 NNAS electrodes exhibit excellent cycling stability at 1.5 C(1141 mAh g^–1 after 1950 cycles).The discharge capacity of 60 NNAS electrodes with more active material is 490mAh g^–1 at 2.5 C after 1000 cycles.4.A series of Ni–Co alloy nanocones arrays were fabricated by means of electrodeposition method without using any template.The aspect ratio of the alloy cones was found to increase with increasing cobalt content within a certain range.The growth and evolution mechanism of alloy nanocone is researched by means of TEM,SEM,XRD.The size of the alloy nanocone structure is controllable by changing the growth time,temperature,alloy composition and crystallization agent.A number of twins are observed through TEM in alloy nanocone with high cobalt content,because the addition of cobalt element can reduce the stacking fault energy drastically.5.The alloy nanocone above is electrodeposited on the Cu microcone substrate to successfully prepare micro-nano hierarchical structures,which increase the specific surface area further.Ni–Co alloy-based three-dimensional hierarchical nanostructures present excellent catalytic performances of the HER.The exchange current density of the hierarchical nanostructures is 6.7-21.9 times as much as that of planar nickel electrode,which can be mainly ascribed to the increasing specific surface area and the synergistic effect of nickel and cobalt atoms.更多还原