Studies of Local Structure and Transport Properties of Anionic Conductors and Battery Materials with Solid State NMR

9901308灰色固态核磁共振（NMR）将用于探测氟化物阴离子导体、铁电氟氧化物和锂锰氧化物阴极材料的局部结构。在这些系统中，了解局部结构以及它如何随温度（氟化物）或电池（锂锰氧化物）的充电/放电而变化对于理解这些材料的功能至关重要。氟化物和氟氧化物中氟离子传导的机制将被确定。无序和氟离子迁移率在控制铁电体铁电到顺电相变中的作用将被研究。锂锰氧化物可用作锂可再充电电池或“摇椅”电池的阴极材料。然而，由于这些电极材料存在再现性问题，并且在电化学电池的重复充电和放电之后会损失容量，因此NMR将用于跟踪充电/放电期间阴极的局部结构（原子和电子）的变化。目的是确定在特定电压下哪些局部锂环境被脱嵌，以及哪些局部锂环境仍然被困在固体中。中到快的离子传导在广泛的设备或应用中是关键的，所述设备或应用包括燃料电池、传感器和电池中的固态电解质（和阴极材料）。对传导机制的理解将有助于为这些应用设计和寻找新的和改进的材料。许多计算机（和电子设备）中的可充电电池通常代表系统的第一个组件失败：为了跟上社会对电动（计算机控制）机械的需求增长，该领域的研究至关重要。锂离子电池阴极代表了目前生产的电池的更环保和更便宜的替代品。

9901308 GreySolid State Nuclear Magnetic Resonance (NMR) will be used to probe local structure in fluoride-anion conductors, ferroelectric oxyfluorides, and lithium manganese oxide cathode materials. These are all systems where knowledge of local structure, and how it changes with temperature (fluorides) or charging/discharging of the battery cell (lithium manganese oxides) is critical to the understanding of the function of these materials. Mechanisms of fluoride-ion conduction in fluorides and oxyfluorides will be determined. The role of disorder and fluroride ion mobility in controlling ferroelectric to paraelectric phase transitions in ferroelectrics will be investigated. Lithium manganese oxides may be used as cathode materials for lithium rechargeable or "rocking chair" batteries. Since these electrode materials, however, suffer from reproducibility problems, combined with a loss of capacity after repeated charging and discharging of the electrochemical cell, NMR will be used to follow the changes in local structures (atomic and electronic) of the cathode during the charging/discharging. The aim is to determine which local lithium environments are deintercalated at a spec fic voltage, and which lithium local environments remain trapped in the solid.%%%Moderate to fast ionic conduction is critical in a wide range of devices or applications, which include fuel cells, sensors, and solid state electrolytes (and cathode materials) in batteries. An understanding of the mechanisms of conduction will help in the design and search for new and improved materials for these applications. The rechargeable battery in many computers (and electronic devices) typically represents the first component of the system to fail: research in this area is critical in order to keep pace with society's increased demand for electrically driven (computer controlled) machinery. The manganate cathodes represent more environmentally-friendly and cheaper alternatives to batteries currently in production.