硫化锌石墨烯复合纳米材料的合成与在锂离子电池中的应用

发布时间：2018-04-20 01:26

  本文选题：锂离子电池 + ZnS　； 参考：《浙江大学》2017年硕士论文

【摘要】：社会发展到今天,人们对能源的依赖程度越来越深,提供能源的储能设备越来越受到人们的重视。其中锂离子二次电池受到全世界的广泛关注。传统的锂离子电池已经无法满足人们要求,提高储能设备的性能,是社会亟待解决的问题。负极是电池重要的组成部分,目前市场上常用的石墨负极,基本已经接近理论比容量,已达到材料的上限。合金类、金属氧化物、金属硫化物具有高比容量、低成本、环境友好和安全性高等优点,一直被认为是极具潜力的下一代负极材料。然而,该类负极材料在充电过程中体积变化巨大、及氧化物硫化物导电性能差的问题,导致活性物质粉化脱离主体,有效成分得不到有效利用,造成循环寿命差,阻碍进一步实用化。我们以金属ZnS为研究对象,对于其体积变化大和导电性差的问题,从以下方面对材料进行改进;在材料中引入高导电性碳材料石墨烯(rGO),氧化石墨烯水溶液中引入锌盐离子,具有高的比表面积,且表面有各种含氧基团,能够结合锌盐正离子。经过高温水热反应,我们得到了具有特殊结构复合材料,即石墨烯表面负载半球形空心纳米ZnS颗粒的ZnS/rGO复合材料。通过控制温度、原料配比得到不同形貌的复合材料,当ZnS与GO比例达到1:1,反应温度为180℃时,得到空心ZnS颗粒粒径为200 nm左右,在电流密度为100 mAg-1时,30次循环比容量仍有510 mAhg-1。通过增加还原剂葡萄糖尿素聚合树脂的量和600℃高温处理的手段,我们将石墨烯表面ZnS颗粒尺寸降到几个纳米大小,并在石墨烯表面成功覆盖一层碳层。100次循环后比容量仍有714 mAhg-1。引入Fe元素,水热过程直接加入Fe2+盐,通过一步反应得到掺杂Fe的ZnS/rGO-Fe复合材料,由SEM分析看出,材料仍然保持原来的半球空心形貌,XRD图谱分析,铁元素以FeS的形式存在。在电流密度为100mAhg-1,循环性能表现较好,100次循环后,剩余可逆比容量接近600 mAhg-1。我们将材料利用高温熔融的方法,进行载硫处理,在ZnS/rGO表面均匀覆盖一层单质硫,通过对不同原料配比的复合物进行载硫和锂硫电池电化学性能测试,探讨ZnS的量对锂硫电池电化学行为的影响。研究发现当原料配比为10:1时,电池性能最好,100次循环后,可逆比容量仍有921 mAhg-1,容量保持率为90.5%。
[Abstract]:Nowadays, people depend more and more on energy, and more and more attention is paid to energy storage equipment. Among them, lithium ion secondary battery has been paid more and more attention all over the world. Traditional lithium ion batteries can not meet the needs of people. It is an urgent problem to improve the performance of energy storage equipment. Negative electrode is an important part of battery. Graphite anode, which is commonly used in the market at present, is close to the theoretical specific capacity and has reached the upper limit of material. Alloys, metal oxides and metal sulfides have been considered as the next generation of anode materials with high specific capacity, low cost, environmental friendliness and high safety. However, the large volume change in the charging process and the poor conductivity of oxide sulfides lead to the pulverization of active substances from the main body, and the lack of effective utilization of the active components, resulting in poor cycle life. Hinders further application. Taking metal ZnS as the research object, we improve the material from the following aspects: the introduction of high conductivity carbon material graphene rgol, the introduction of zinc salt ion in graphene oxide aqueous solution, the high conductivity carbon material, the high conductivity carbon material, the high conductivity carbon material, the high conductivity carbon material, the high conductivity carbon material, the zinc salt ion in the aqueous solution of graphene oxide. It has high specific surface area and various oxygen groups on the surface, which can bind zinc salt positive ions. By hydrothermal reaction at high temperature, we have obtained the ZnS/rGO composite with special structure, that is, the graphene surface loaded with hemispherical hollow ZnS particles. When the ratio of ZnS to go is 1: 1 and the reaction temperature is 180 鈩，

本文编号：1775631