项目名称： 锂离子电池用高容量富锂层状氧化物双晶畴结构演化机制研究

项目编号： No.U1507107

项目类型： 联合基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 尉海军

作者单位： 北京工业大学

项目金额： 40万元

中文摘要： 高容量富锂层状氧化物（LLOs）是下一代锂离子电池用正极材料的研究热点。目前已知LLOs的电化学性能与其结构演化密切相关，但机制不明。我们的前期研究已揭示了LLOs的双晶畴（Monoclinic Li2MnO3结构与Rhombohedral LiTMO2结构）共存特征，利用电化学方法证明了LLOs内Li2MnO3结构的活化，初步证实了双晶畴反应机制的可能性。本研究拟在前期的工作基础上，建立LLOs的结构与制备方法和组分的关系，揭示晶体内Li2MnO3和LiTMO2结构的分布、界面、结合方式，深入研究双晶畴在首圈充放电和长时间循环过程中的平均和局部结构演化，并借助第一性原理分析结构演变与电化学性能的关系，建立完整的LLOs双晶畴反应机制，为材料性能的改善提供依据。本项目的实施对深入了解LLOs的高容量特征和改善LLOs的电化学性能具有重要意义，为开发其它复合层状氧化物电极材料奠定理论基础。

中文关键词： 高容量；锂离子电池；双晶畴；结构演化；反应机制

英文摘要： High-capacity lithium-rich layered oxides (LLOs) are the hot research topic for positive materials of next generation lithium-ion batteries. Currently, it is generally believed that the relationship between electrochemical performance and structure evolution of LLOs is closely related, while the reaction mechanism is unclear. Our previous researches had revealed the two crystal domains (Monoclinic Li2MnO3 and Rhombohedral LiTMO2) coexistence, given the indirect evidences for Li2MnO3 structure activation by electrochemical methods, and proved the possibility of two phase reaction mechanism tentatively. Therefore, this research will based on our previous research results, establish the relationship between the structure and composition or preparation method, reveal the Li2MnO3 and LiTMO2 crystal domains distribution, interface and combination a single grain, research the average and local structure evolutions deeply of two structures during initial charge/discharge and long-term cycle processes, analysis the relationship between structure evolution and electrochemical performance through first-principle calculation method, and establish the integrate reaction mechanism of LLOs with two crystal domains. The implementation of this project has important significance on understanding the high capacity characteristic deeply and electrochemical performance improvement of LLOs, and also lays the theoretical foundation for developing other composite layered oxides for utilization as electrodes in different secondary batteries.

英文关键词： High capacity;litium ion batteries;two crystal domains;structure evolution;reaction mechanism