乙二胺四乙酸系列金属配合物的合成、热化学性质及锂离子电池性能研究

发布时间：2018-01-18 02:35

本文关键词：乙二胺四乙酸系列金属配合物的合成、热化学性质及锂离子电池性能研究　出处：《聊城大学》2017年硕士论文　论文类型：学位论文

【摘要】：乙二胺四乙酸(简称EDTA)是一种常见的络合剂,因具有强烈的配位能力,常用作核酸酶、蛋白酶抑制剂、染色助剂、化妆品添加剂、血液抗凝剂、合成橡胶聚合引发剂、水处理剂等,因此,在食品加工、医疗卫生、化工生产及纳米材料组装等方面备受关注。目前,这类配合物的合成、结构及性能表征方面已取得重大进展。然而,对其热化学性质方面及新领域应用方面的研究,文献中少有报道。为了进一步提升这一类配合物在工业生产及新领域的应用,本文从乙二胺四乙酸金属配合物单晶结构出发,研究其热力学方面的性质以及热分解乙二胺四乙酸锰金属配合物制备MnO/N-C复合材料并研究在锂离子电池中的应用。研究工作主要分为以下几个部分:1.乙二胺四乙酸系列金属配合物的合成及结构表征。首先,合成九种乙二胺四乙酸金属配合物;然后,用X-射线单晶衍射仪测定配合物的结构及组成;最后,以得到的晶体数据,绘制各配合物的晶体结构图;从晶体结构可以看出,该系列配合物均为含水化合物,同一主族中,随原子序数和原子半径增大,中心原子最大配位数逐渐增加;从晶格能的变化可以看出,由于金属离子电荷的变化,碱土金属的晶格能大于碱金属系列的晶格能,同时,对于同一主族而言,分子体积大的晶格能相对较小。2.乙二胺四乙酸系列金属配合物的热化学性质研究。具体分为两部分:(1)配合物摩尔热容的测定及热力学函数值的确定。首先,利用精密自动绝热热量计测定乙二胺四乙酸系列金属配合物在78-400 K温度区间内的摩尔热容;然后,根据测定的摩尔热容,用最小二乘法得到热容关于温度变化的多项方程,利用方程,得到相对于298.15 K时的热力学函数值。摩尔热容的测定结果说明,所合成的该类系列配合物在78-400 K温度区间内结构稳定,除乙二胺四乙酸钙之外,同一主族中,摩尔热容随分子量的增加而增加,并且相关基础热力学函数值的绝对值也符合该趋势。(2)配合物标准摩尔生成焓的测定。首先,根据Hess定律,设计合理的热化学循环,选定合适的量热溶剂;然后,利用等温环境溶解-反应热量计测定热化学反应中各物质的溶解焓,根据溶解焓计算出热化学反应的反应焓;然后,根据所计算的反应焓和已知物质的标准摩尔生成焓计算出目标配合物的标准摩尔生成焓;最后,利用紫外可见光谱验证热化学反应循环的合理性。由该系列配合物的标准摩尔生成焓的测定结果看出,所合成的九种乙二胺四乙酸金属配合物的能量较低,结构比较稳定。对于同一主族金属元素的配合物而言,除乙二胺四乙酸铯和乙二胺四乙酸钡之外,其他配合物的标准摩尔生成焓的绝对值呈随分子量的增大而增大的趋势。3.热分解乙二胺四乙酸锰金属配合物制备MnO/N-C复合材料并研究其作为负极材料在锂离子电池中的应用。针对MnO负极材料循环性能较差的缺点,通过对负极材料实现碳、氮共掺杂提升锂离子电池性能。首先以溶剂挥发法制备了乙二胺四乙酸锰的单晶,通过在氩气中煅烧前驱体的方法获得了碳、氮共掺杂的MnO/N-C复合纳米结构,进而研究了该材料作为负极材料在锂离子电池中的应用。实验探讨了不同的煅烧温度对负极材料组成、形貌结构以及锂离子电池性能的影响。实验结果表明,在400°C下煅烧后,负极材料表现出优异的循环性能,在1 A g~(-1)的电流密度下,循环800圈,仍能保持874.4 mAhg~(-1)的比容量。
[Abstract]:Ethylenediaminetetraacetic acid (EDTA) is a kind of complexing agent, with strong coordination ability, commonly used as a DNA enzyme, protease inhibitors, dyeing auxiliaries, cosmetic additives, blood anticoagulant, synthetic rubber polymerization initiator, water treatment agent, therefore, in food processing, medical and health, chemical production and assembly of nano materials other aspects of concern. At present, this kind of complexes, significant progress has been made in the characterization of structure and properties. However, the research on the application and the new field of thermochemistry aspects, the literature rarely reported. In order to further improve this kind of complexes in the fields of industrial production and application, this article from the the crystal structure of metal EDTA COMPLEXES, study the thermodynamic properties and thermal decomposition of manganese metal EDTA MnO/N-C composites were prepared and studied in lithium ion complex system The application of batteries. The main research work is divided into the following parts: synthesis and characterization of the 1. series of EDTA metal complexes. Firstly, synthesis of nine kinds of metal EDTA complexes; then, the determination of the complex structure and composition by X- ray diffractometer; finally, to get the crystal data, crystal structure drawing the complexes; from the crystal structure can be seen, the complexes are hydrated compounds, the same main group, with the atomic number and atomic radius, central atom maximum coordination number increases gradually; from the change of lattice energy can be seen, due to changes in metal ion charge, alkaline earth metal lattice can be greater than the lattice energy of alkali metal series, at the same time, for the same main group, molecular volume large lattice can relatively small.2. EDTA series metal complex thermochemical properties of objects. The specific Is divided into two parts: (1) determination and thermodynamic function values of the molar heat capacity of cooperation. Firstly, measured molar heat capacity at 78-400 K temperature range of EDTA series of metal with the use of precision automatic adiabatic heat; then, according to the molar heat capacity determination, obtained by the least square method on the temperature change of the heat capacity of a number of equations use, equation, thermodynamic functions relative to a value of 298.15 K. The testing results of the molar heat capacity, the synthesis of the complexes structure stability in the 78-400 K temperature range, in addition to four ethylenediamine calcium acetate, the same main group, molar heat capacity with the molecular weight increased, and the absolute value basic thermodynamic function values is also consistent with the trend. (2) the standard molar enthalpies of formation of complexes were determined. Firstly, according to the Hess law, the rational design of the thermochemical cycle, selected suitable quantity of heat Then, the solvent; enthalpy of dissolution of each substance in meter by thermochemical reaction isoperibol solution reaction heat, reaction enthalpy calculated thermochemical reaction according to the enthalpy of dissolution; then, calculate the standard molar enthalpy of formation target complexes according to standard molar reaction enthalpy calculation and the enthalpy of the known material; finally, the use of UV Vis spectra verify rationality of thermochemical reaction cycle. From the testing results of this series of standard molar enthalpies of formation of complexes, nine kinds of metal EDTA complexes of low energy, relatively stable structure. For the complexes of the same main group metal elements, in addition to cesium and barium ethylenediaminetetraacetic acid EDTA absolute value, standard molar enthalpy of formation of other complexes showed a trend of.3. heat increases with the molecular weight of the decomposition of EDTA manganese metal complexes preparation MnO/N-C composite material and Study on its application as anode materials in lithium ion batteries. The poor cycle performance of MnO anode materials based on anode material defects, carbon, and nitrogen Co doped to improve the performance of lithium ion battery. The first single crystal prepared by solvent evaporation method EDTA manganese, obtained by calcination method of carbon precursor in argon, nitrogen Co doped MnO/N-C composite nano structure, and studied the application of the material as anode materials in lithium ion batteries. Experimental study of different calcination temperature on the composition of anode material, morphology structure and properties of lithium ion batteries. The experimental results show that under the temperature of 400 C calcined anode the material exhibits excellent cycling performance, in 1 A g~ (-1) of the current density, 800 cycles, still can maintain 874.4 mAhg~ (-1) than the capacity.

【学位授予单位】：聊城大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.4;TM912

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