Collaborative Research: Synthesis, Structural Characterization and Electrochemical Studies of Framework Substituted Silicon, Germanium and Tin Clathrates

非技术摘要：晶体材料的结构完整性是很大程度上影响其实际应用能力的重要性质。对于电化学储能设备，日常操作涉及到离子的电化学插入和提取，这往往伴随着可能导致材料坍塌的较大结构转变。因此，为了实现未来的储能需求，寻找新的电极材料是必要的。笼状物是一类具有笼状结构的材料，可以自然地容纳客体离子，这一特征可能会被利用在储能应用中。然而，笼状粘结结构中的不同特征可能会影响其机械完整性。这个项目的主要目标是了解这些材料的电化学特性，当客体离子电化学插入时，包合物的结构是如何变化的，以及开发新的合成路线来获得包合物。这个项目的结果使人们对笼形化合物之间的复杂关系有了新的了解？技术摘要：该项目的目标是：(1)利用第一性原理计算和详细的结构表征来研究Ge和TiN包合物的电化学性质和结构性质，以了解电化学得到的结构；(2)从新的前驱体合成新的含锂离子的包合物。该项目采用了一种协调一致的方法，结合了研究人员的合成、结构和电化学表征以及理论专业知识。这项研究有助于更好地了解包合物结构与其物理性质、电化学性质和相稳定性之间的关系。这些成就可能会导致锂和钠电池的能量密度更高。这些研究还有助于建立固态化学的预测能力，建立关于原子为什么以及如何组装并形成具有所需电化学性质的新化合物和结构的新想法。对这些材料的调查涉及两所大学(亚利桑那州立大学和特拉华大学)和三个不同的系(材料科学、化学和物理)之间的合作，这让学生接触到多学科的研究。推广和教育活动，吸引从中学到本科生的学生，重点是招收女性进入科学和工程专业，并改善学生在本科入门课程中的学习和参与程度。

Nontechnical Abstract:The structural integrity of a crystalline material is an important property that can greatly influence its ability to be utilized in practical applications. For electrochemical energy storage devices, daily operation involves the electrochemical insertion and extraction of ions, which is often accompanied by larger structural transformations that may cause the material to collapse. Hence, the search for new electrode materials is necessary in order for future energy storage demands to be realized. Clathrates are a class of materials with cage-like structures that can naturally hold guest ions, a feature that may be exploited in energy storage applications. However, different features in the clathrate bonding arrangement may affect its mechanical integrity. Key objectives of this project are to understand the electrochemical characteristics of these materials, how the structure of the clathrate changes upon electrochemical insertion of guest ions, and the development of new synthetic routes to obtain clathrates. Results from this project enable new knowledge on the intricate relationships among the clathrates? structures and their physical properties, electrochemical characteristics, and structural stability.Technical Abstract:The objectives of this project are: (1) to investigate the electrochemical and structural properties of germanium and tin clathrates using first principles calculations and detailed structural characterization to understand the electrochemically obtained structures; and (2) to synthesize new clathrates containing lithium ions from novel precursors. The project uses a concerted approach combining the synthetic, structural and electrochemical characterization, and theoretical expertise of the investigators. The research enables a better understanding of the relationship between the clathrate structure and its physical properties, electrochemical characteristics, and phase stability. These achievements could lead to higher energy density lithium and sodium batteries. The studies also help to build up the predictive power of solid-state chemistry, establishing new ideas of why and how atoms assemble and form new compounds and structures with the desired electrochemical properties. Investigation of these materials involves a collaboration between two universities (Arizona State University and University of Delaware) and three different departments (materials science, chemistry, and physics), which exposes students to multidisciplinary research. Outreach and educational activities engaging students ranging from the middle school to undergraduate levels, with an emphasis on recruiting females into science and engineering and improving student learning and engagement in introductory undergraduate classes.