金属硫化物及其复合纳米材料的制备及其储锂性能研究
发布时间：2018-07-18 11:49
【摘要】：锂离子电池作为新兴储能电池,被广泛研究应用于电子设备和混合动力电动车。而对于锂电的研究主要是集中在电极方面,其关键是寻找高容量,高能量密度的电池材料。目前已经商业化的锂电负极材料主要是石墨材料,其电导率高,但理论容量低(372 m Ah g-1),因此关于负极材料的研究开始转向其他材料。目前发现金属硫化物拥有非常高的理论容量,如Mo S2的理论容量为(670 m Ah g-1)。但是由于其存在电导率较低、在充放电过程会有体积坍塌现象,而这些问题主要是从以下两个方面来解决,(1)合成特殊的纳米结构来支撑材料不坍缩;(2)通过和其他纳米材料(如石墨烯、金属氧化物以及金属硫化物)复合,通过协同效应,来提高整体材料的比容量以及抵抗抗体积效应的能力。本章主要是通过上述两个方面来提高金属硫化物在锂离子电池中的各方面性能,主要内容如下:1、利用牺牲模板法合成由二维Mo S2纳米片组装的三维Mo S2纳米管,通过对纳米管形成过程的研究,探索其这种特殊纳米结构的形成机理,并将其制备成电极材料,展现出了优秀的电化学性能。同时还深入研究其在循环后形貌和组分的变化,进一步阐明整个材料的充放电过程以及性能优越性的原因。2、进一步探究了以三氧化钼为模板制备二硫化钼方法的普遍适用性,用此方法合成二维Mo S2纳米片组装的多孔Mo S2纳米片,并对其进行高温煅烧,提高其电化学性能。通过对比煅烧前后多孔Mo S2微纳米片和Mo S2纳米管的电化学性能,发现煅烧后的多孔Mo S2微纳米片具有最佳储锂性能,同时对循环后负极材料进行形貌和组分分析表征,分析了煅烧后材料性能优越的原因。3、本章通过两步溶剂热法合成出Co9S8@Mo S2/r GO三元复合物材料,其中Mo S2纳米片生长在Co9S8的表面,并形成了纳米核壳结构。文中探索了钴和钼盐不同负载量的三元复合材料,同时还合成Co9S8/r GO二元复合材料,依据对其以及前两章二硫化钼的脱锂嵌锂的研究,进一步推测三元复合材料的脱锂嵌锂过程,同时经过对二元和三元复合材料的电化学性能的对比,突出Co9S8@Mo S2核壳结构的优越性。并通过对循环后负极材料的表征,阐明该三元复合材料电化学性能优越的原因。
[Abstract]:As a new energy storage battery, lithium ion battery has been widely used in electronic devices and hybrid electric vehicles. The research of lithium is mainly focused on the electrode, the key is to find high capacity, high energy density battery materials. At present, the commercial lithium anode materials are mainly graphite materials with high conductivity but low theoretical capacity (372mAh g-1). Therefore, the research on anode materials has turned to other materials. At present, it has been found that metal sulfides have very high theoretical capacity, such as the theoretical capacity of Mo S2 is (670 mAh / g ~ (-1). However, due to its low conductivity, there will be volume collapse in the charge-discharge process. These problems are solved mainly in the following two aspects: (1) the synthesis of special nanostructures to support the material from collapsing; (2) the synergistic effect of combining with other nanomaterials (such as graphene, metal oxides and metal sulphides). To improve the specific capacity of the whole material and the ability to resist the volume effect. In this chapter, the properties of metal sulfides in lithium ion batteries are improved through the above two aspects. The main contents are as follows: 1. The three-dimensional MoS2 nanotubes assembled by two-dimensional MoS2 nanoplates were synthesized by sacrificial template method. Through the study of the formation process of nanotubes, the formation mechanism of this special nanostructure was explored, and the electrode materials were prepared, showing excellent electrochemical properties. At the same time, the changes of morphology and composition after cycling were also studied, the charge-discharge process of the whole material and the reasons for its performance superiority were further elucidated, and the universal applicability of the method of preparing molybdenum disulfide with molybdenum trioxide as template was further explored. The porous MoS2 nanoparticles were synthesized by this method and calcined at high temperature to improve their electrochemical properties. By comparing the electrochemical properties of the porous MoS2 microchips and MoS2 nanotubes before and after calcination, it was found that the calcined porous MoS2 microchips had the best lithium storage performance, and the morphology and composition of the cyclic anode materials were characterized. In this chapter, Co9S8MoS2 / r go ternary composite material was synthesized by two step solvothermal method. MoS2 nanocrystalline grown on the surface of Co9S8 and formed nanocrystalline core-shell structure. In this paper, ternary composites with different amounts of cobalt and molybdenum salts were investigated. Co9S8 / r go binary composites were also synthesized. Based on the study of the delithium intercalation of molybdenum disulfide and the former two chapters, the delithium intercalation process of the ternary composites was further speculated. At the same time, the advantages of Co9S8MoS2 core-shell structure are highlighted by comparing the electrochemical properties of binary and ternary composites. The reason for the excellent electrochemical performance of the ternary composite was explained by the characterization of the negative electrode material after the cycle.
【学位授予单位】：安徽师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;TM912
本文编号：2131812
[Abstract]:As a new energy storage battery, lithium ion battery has been widely used in electronic devices and hybrid electric vehicles. The research of lithium is mainly focused on the electrode, the key is to find high capacity, high energy density battery materials. At present, the commercial lithium anode materials are mainly graphite materials with high conductivity but low theoretical capacity (372mAh g-1). Therefore, the research on anode materials has turned to other materials. At present, it has been found that metal sulfides have very high theoretical capacity, such as the theoretical capacity of Mo S2 is (670 mAh / g ~ (-1). However, due to its low conductivity, there will be volume collapse in the charge-discharge process. These problems are solved mainly in the following two aspects: (1) the synthesis of special nanostructures to support the material from collapsing; (2) the synergistic effect of combining with other nanomaterials (such as graphene, metal oxides and metal sulphides). To improve the specific capacity of the whole material and the ability to resist the volume effect. In this chapter, the properties of metal sulfides in lithium ion batteries are improved through the above two aspects. The main contents are as follows: 1. The three-dimensional MoS2 nanotubes assembled by two-dimensional MoS2 nanoplates were synthesized by sacrificial template method. Through the study of the formation process of nanotubes, the formation mechanism of this special nanostructure was explored, and the electrode materials were prepared, showing excellent electrochemical properties. At the same time, the changes of morphology and composition after cycling were also studied, the charge-discharge process of the whole material and the reasons for its performance superiority were further elucidated, and the universal applicability of the method of preparing molybdenum disulfide with molybdenum trioxide as template was further explored. The porous MoS2 nanoparticles were synthesized by this method and calcined at high temperature to improve their electrochemical properties. By comparing the electrochemical properties of the porous MoS2 microchips and MoS2 nanotubes before and after calcination, it was found that the calcined porous MoS2 microchips had the best lithium storage performance, and the morphology and composition of the cyclic anode materials were characterized. In this chapter, Co9S8MoS2 / r go ternary composite material was synthesized by two step solvothermal method. MoS2 nanocrystalline grown on the surface of Co9S8 and formed nanocrystalline core-shell structure. In this paper, ternary composites with different amounts of cobalt and molybdenum salts were investigated. Co9S8 / r go binary composites were also synthesized. Based on the study of the delithium intercalation of molybdenum disulfide and the former two chapters, the delithium intercalation process of the ternary composites was further speculated. At the same time, the advantages of Co9S8MoS2 core-shell structure are highlighted by comparing the electrochemical properties of binary and ternary composites. The reason for the excellent electrochemical performance of the ternary composite was explained by the characterization of the negative electrode material after the cycle.
【学位授予单位】：安徽师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;TM912
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