新型钼基负极材料的电化学性质与储能机制的研究

发布时间：2018-02-02 08:32

本文关键词： 锂离子电池钠离子电池钼基材料负极材料储能机制　出处：《吉林大学》2017年博士论文　论文类型：学位论文

【摘要】：钼基负极材料在电化学反应过程中会发生多电子反应,最高可实现6摩尔的离子存储,高出3d过渡金属氧化物2~3倍左右,因此被认为是极具应用前景的新一代二次电池负极材料。但是大量离子的嵌入与脱出,通常会诱导电极材料发生剧烈的体积膨胀与收缩,导致容量急剧衰减、循环稳定性变差等问题。如何获得兼具高比容量与良好循环稳定性的优异电极材料就成为亟待解决的关键问题。本论文以不同钼基化合物为研究对象,深入电极材料的储能机制层面,探讨负极材料在电化学过程中的结构与相变过程;并利用不同化合物在储能过程中的协同作用,获得了多种循环与倍率性能优异的负极材料。我们首先研究了聚阴离子型负极材料Li Fe(Mo O4)2的电化学性质与其储锂机制,通过铁与钼的转换反应实现了高的放电比容量。其次,采用固相法合成了钛铀矿型Li VMo O6。该材料在首次放电过程中分解形成钒氧化物和钼单质。利用不同储锂机制(嵌入脱出过程与转换反应)之间的协同作用,实现了高的循环可逆比容量和出色的倍率性能。在此基础上,设计并制备了新型钛铀矿结构材料Na VMo O6,并深入探讨了其在锂离子与钠离子电池中的电化学性质与储能机制的差异。最后,首次将Ag2Mo2O7作为钠离子电池负极材料来使用。材料在首次放电过程中生成的单质银纳米颗粒有利于提高电子电导率,优化倍率性能;而嵌入脱出的储钠机制使材料具有更稳定的循环属性。本论文开展的系列研究工作不仅有利于我们深入理解钼基化合物在不同电池体系下的储能过程,同时也为设计新型负极材料提供了新思路和新见解。
[Abstract]:The molybdenum based anode material can react with multiple electrons during the electrochemical reaction. The maximum ion storage is 6 moles, which is about 3 times higher than that of the transition metal oxide of 3 days. Therefore, it is considered to be a new generation of negative electrode materials for secondary batteries. However, the insertion and removal of a large number of ions usually induce the electrode materials to expand and shrink sharply, which leads to the rapid decline of the capacity. How to obtain excellent electrode materials with both high specific capacity and good cyclic stability has become a key problem to be solved. In this paper, different molybdenum based compounds are taken as the research object. The structure and phase transition process of negative electrode materials in electrochemical process are discussed in the layer of energy storage mechanism of electrode materials. The synergism of different compounds in the process of energy storage was also utilized. A variety of cathode materials with excellent cycling and rate properties were obtained. Firstly, the electrochemical properties and lithium storage mechanism of polyanionic cathode material Li Fe(Mo O 4O 4 were studied. Through the conversion reaction between iron and molybdenum, a high discharge capacity was achieved. Titanium uranium type Li VMo O 6 was synthesized by solid state method. The material was decomposed into vanadium oxide and molybdenum in the first discharge process. Different lithium storage mechanisms were used (intercalation process and transition reaction). The synergy between. On the basis of this, a new type of titanium uranium structure material Na VMo O 6 was designed and prepared. The differences of their electrochemical properties and energy storage mechanism in lithium ion and sodium ion batteries were also discussed. Ag2Mo2O7 was used as anode material for sodium ion battery for the first time. The silver nanoparticles formed in the first discharge process were helpful to improve the electronic conductivity and optimize the performance of the cathode. The intercalated mechanism of sodium storage makes the material have more stable cycling properties. The series of research work in this paper is not only helpful for us to understand the energy storage process of molybdenum based compounds in different battery systems. At the same time, it also provides new ideas and new ideas for the design of new negative electrode materials.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM912;TQ13

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