SnO/C和Sn/C复合材料的制备及其在锂离子电池中的应用

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	SnO/C和Sn/C复合材料的制备及其在锂离子电池中的应用
	谭智
学位类型	硕士
导师	苏党生 ; 孙振华
	2012
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料物理与化学
关键词	锂离子电池锡氧化锡碳材料复合材料 Lithium Ion Battery Tin Tin Oxide Carbon Materials Composite
其他摘要	" 首先，本文发展了一种制备一氧化锡/碳复合材料的新方法。采用一种简单的离子交换法，将锡离子负载到树脂上面，再通过在惰性气氛中碳化，成功地制备了一氧化锡/碳复合材料。经过表征，所得到的材料为一种微纳米结构，纳米尺寸的一氧化锡粒子很好地包裹在几个微米碳基体颗粒内。这样一种结构有利于碳基体对一氧化锡的纳米粒子起到较好的保护作用，又避免了单独存在的高表面能的纳米粒子形成的安全隐患，并且材料整体表现为微米粒子使其具有高的振实密度。通过电化学性能测试，材料表现出了高的嵌锂容量与稳定的循环充放电性能。通过对实验条件的改变，制备出了锡/碳复合材料，提高了材料首次充放电的库仑效率。为了改善锡/碳复合材料循环充放电的稳定性能，本文对不同的材料制备工艺进行了探索，改善了材料的内部结构，在锡/碳复合材料的碳基体中形成了大量的微孔与中孔。电化学性能测试的结果表明，这种多孔结构的锡/碳复合材料有较好循环稳定性能。锡/碳复合材料的孔结构在充放电过程中能有效地缓解材料中锡粒子的体积膨胀，对于改善材料的循环稳定性能有很大的帮助。将多孔结构的锡/碳复合材料进行了表面包碳的处理，在材料的表面上包上了一层无定形碳。包碳处理后，材料中所有的锡粒子都被无定形碳很好地包裹起来，材料在空气中显示了很好的热稳定性能。包碳后的锡/碳复合材料的比表面极大的减小，其首次充放电过程中的库仑效率有很大的提高。表面的碳包覆能对材料起到进一步的保护作用，使其充放电循环的性能更加稳定。本论文发展的材料制备方法新颖，过程简单，成本低，对于商业化的大规模生产、高容量的锡基负极材料有很好的借鉴意义。所制备的一氧化锡/碳，锡/碳复合材料结构优异，容量高，性能稳定，并且通过表面包碳技术大幅提高了材料首次充放电的库仑效率，其在新一代高容量的锂离子电池中有潜在的应用价值。 "; " Energy crisis and environmental pollution are two major problems the international community has to face in 21 century. The utilization of all sorts of renewable green energy resources is arousing more and more attention. For them, energy storage is a key step. Chemical power sources, which are based on the conversion between chemical energy and electric energy that could afford a steady power output, are the most widely used energy storage device. Compared to other secondary batteries, lithium ion batteries have a lot of advantages, such as high energy density, high open circuit voltage, excellent cycle performance, no memory effect, low self-discharge rate, friendly to environment. Up to now, lithium ion batteries have held the market of portable electronics. However, the trend of micromation and intellectualization of electronic products and the transformation of the automobile industry into electric vehicles put an exigent demands on lithium ion batteries for higher energy density and better security. Based on such background, in this paper, tin based materials, which show higher lithium storage capacity and better security than commercial graphite materials, were studied as negative electrode in lithium ion batteries. New methods were applied for the materials preparation, and different treatment technologies were explored to improve the properties of the materials. A new method was developed for the synthesis of hybrid structure of tin monoxide and carbon (SnO/C). At first, tin ions were loaded onto resin by a novel and simple ion-exchange method. After subsequent carbonization process, SnO/C composite is finally obtained. The structure of the as prepared SnO/C was characterized. SnO is nanoparticles that were well confined in amorphous carbon microparticles. Carbon matrix in micrometer scale not only acts as a protective buffer for the SnO nanoparticles during the battery cycling processes, but also avoids the shortcomings of nanostructures, such as low tap density and potential safety threats. Electrochemical behaviors of the SnO/C composite were tested as anode material in lithium ion batteries. High reversible lithium storage capacity and stable cycle performance were exhibited by SnO/C composite. Sn/C composite material is prepared by change the preparation conditions of SnO/C composite. Sn/C composite show higher initial coulombic efficiency than SnO/C composite, but it is not so stable. Different treatment technologies were explored to improve the structure of Sn/C composite. After treatment technologies improvement, A lot of micro- and mesopores were formed on the carbon matrix of the Sn/C composite. The cycle performance of the porous Sn/C composite was greatly improved. This is because the pores in the material can relieve the huge volume expansion of tin particles during Li ions insertion processes. A surface carbon encapsulation technology was developed, and it was applied to the porous Sn/C composite. After surface carbon encapsulation, the surface area of the Sn/C composite was greatly reduced, and its initial coulombic efficiency as negative electrode is greatly improved. In addition, carbon layer on the surface can provide protection to the Sn/C composite, which make the material more stable during charge/discharge processes. The novel material synthesis method developed in the paper combines the advantages of simplicity, low cost, environment-friendly and easy to large scale production, which provides a new idea for the synthesis of new generation high-capacity hybrid anode materials. The enhanced electrochemical properties of the SnO/C and Sn/C composites show great potential value in application.
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64530
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	谭智. SnO/C和Sn/C复合材料的制备及其在锂离子电池中的应用[D]. 北京. 中国科学院金属研究所,2012.