有机电正极材料蒽醌及菲醌衍生物取代基效应的理论研究

发布时间：2018-12-15 07:53

【摘要】：本论文主要应用计算化学的原理,选择适宜的计算方法和中等水平的基组研究锂离子电池体系。研究内容分为两大部分,第一部分介绍吸电子取代基团的数目、位置对有机电正极材料蒽醌和菲醌衍生物的氧化还原电位和能量密度的影响;第二部分对非水有机电解液体系中锂离子与溶剂分子中的官能团之间的相互作用进行了详细的分析。第一章绪论中简单阐述了锂离子电池的电正极材料和电解质溶液的研究近况和有机电正极材料的分类及性能;介绍了计算模拟过程中涉及的理论计算方法、包含溶剂模型、芳香性判据核独立化学位移,以及AIM理论等。第二章通过密度泛函计算探究杂芳香化合物蒽醌和菲醌的取代基效应,为设计可充电锂离子潜在正极材料提供理论指导。醌类衍生物的氧化还原电位计算值随吸电子取代基团数目的增加而增大。醌类衍生物环上的四个氢原子同时被吸电子取代基取代时氧化还原电位数值最大,然而单取代时却获得最大的质量能量密度。羰基是最有利的活性锂键位点,锂原子和取代基团中的电负性原子可以形成分子内锂键。分子内锂键通过增强锂化态的热力学稳定性来升高氧化还原电位。此外,NICS计算表明含有锂-羰基化学键的衍生物比非锂化态更加稳定。第三章主要对锂离子电池另外一个关键的组成电解液进行了研究。非水有机电解液体系包括锂盐和有机溶剂。通过溶剂分子的HOMO轨道的能量高低判断不同取代基团对溶剂分子抗氧化性的改变,之后通过AIM理论探究氟原子对锂离子与溶剂分子相互作用强度的影响。最后分析取代基团对各种溶剂中锂离子去溶剂化能的影响。
[Abstract]:In this paper, the principle of computational chemistry is applied to study the lithium ion battery system. The research contents are divided into two parts. In the first part, the number and position of electron-absorbing substituents on the redox potential and energy density of anthraquinone and phenanthraquinone derivatives with electromechanical cathode materials are introduced. In the second part, the interaction between lithium ions and functional groups in solvent molecules in non-aqueous organic electrolyte system is analyzed in detail. In the first chapter, the research status of cathode materials and electrolyte solutions for lithium ion batteries and the classification and performance of electromechanical cathode materials are briefly described. The theoretical calculation methods involved in the process of calculation and simulation are introduced, including solvent model, aromatic criterion nuclear independent chemical shift, AIM theory and so on. In chapter 2, the substituent effects of anthraquinones and phenanthraquinones are investigated by density functional calculation, which provides theoretical guidance for the design of rechargeable lithium ion potential cathode materials. The calculated value of redox potential of quinone derivatives increases with the increase of the number of electron sucking groups. The redox potential of the four hydrogen atoms on the ring of quinone derivatives is the largest when they are replaced by the electron-absorbing substituents at the same time, but the maximum mass energy density is obtained by the single substitution. Carbonyl group is the most favorable active lithium bond site. Lithium atom and electronegativity atom in substituent group can form intramolecular lithium bond. The intramolecular lithium bond increases the redox potential by enhancing the thermodynamic stability of the lithium state. In addition, NICS calculations show that the derivatives containing lithium-carbonyl chemical bonds are more stable than the non-lithiated ones. In chapter 3, another key electrolyte for lithium ion battery is studied. Non-aqueous organic electrolyte systems include lithium salts and organic solvents. The energy of the HOMO orbitals of solvent molecules is used to judge the changes of the oxidation resistance of solvent molecules by different substituents. Then the influence of fluorine atoms on the interaction between lithium ions and solvent molecules is investigated by AIM theory. Finally, the influence of substituents on the dissolvability of lithium ions in various solvents was analyzed.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O625.46;TM912

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