Design of Ceramics with Isotropic Superionic Conductivity

非技术摘要：在锂离子电池中，电解液促进锂离子在储存能量的两个电极(正极和负极)之间的传导。更好的固态电解液将有助于开发更安全、寿命更长的电池，并有可能完全消除当前锂离子电池有机电解液技术的易燃性和毒性。该项目将通过评估新的候选化合物和开展基础研究来更好地了解锂离子如何在固体电解质中扩散，从而发现更好的固体电解质。这项工作将得到国家用户设施的衍射研究的支持，这些研究将能够在原子尺度上准确确定固体电解质的晶体结构，从而使人们能够了解离子运动的机制。该项目还将通过每年举办的全国结构分析暑期班，支持对青年研究人员进行高级结构表征方法方面的培训。将固态电解液集成到新一代锂离子电池中，有可能彻底扑灭电池火灾，扩大电动汽车的续航里程，降低成本，并通过提供低成本的负载均衡，促进可再生能源进入电网。技术摘要：在过去的50年里，只有大约6个结构家族的锂离子和钠离子的快离子导体被发现。这项建议的一个主要目标是确定新的超级离子导体，这一目标将得到基础研究的支持，以确定和控制最直接影响离子导电性的结构特征。改进的固态快离子导体的发展可以取代目前锂离子电池系统中主要的易燃性、毒性和寿命问题的有机液体电解液，这将导致更安全的电池和更长的寿命。基础研究将在一种特殊的CuBICON陶瓷基质中进行，以了解和优化室温下离子的导电性。CuBICON陶瓷基质的立方对称性允许离子在所有方向上均匀传输，与大多数其他替代系统不同。首先，将进行化学合成(固相和离子交换)，以制备各种已知和新组成的单相CuBICON材料。接下来，将进行X射线和中子衍射研究，以准确定位原子的位置(能够对离子的成键强度和迁移率进行定性估计和定量计算)。新的原位方法将被应用于确定与其合成相关的离子交换机制。最后，将进行物理性能测量，以评估这些材料的离子和电子导电性，并确定可用于制备具有最佳性能的CuBICON材料的设计规则。

Non-technical Abstract:Within a Li-ion battery, the electrolyte facilitates the conduction of Li ions between the two electrodes (cathode and anode) that store energy. Better solid state electrolytes will enable the development of safer batteries with improved lifetimes, and have the potential to completely eliminate the flammability and toxicity associated with current organic electrolyte technologies for Li-ion batteries. This project will lead to the discovery of better solid state electrolytes both by evaluating new candidate compounds and by carrying out fundamental studies to better understand how Li ions diffuse through solid electrolytes. This work will be supported by diffraction studies at national user facilities that will allow the accurate determination of the crystal structure of solid electrolytes at the atomic scale, allowing the mechanism of ionic motion to be understood. This project will additionally support the training of young researchers in advanced structural characterization methods through a national summer school on structural analysis to be offered every year. The integration of solid state electrolytes into next-generation Li-ion batteries has the potential to completely eliminate battery fires, to extend the range and reduce the cost of electric vehicles, and to facilitate the integration of renewable energy sources into the electrical grid by providing low-cost load leveling.Technical Abstract:In the last 50 years, only about half a dozen structural families of superionic conductors for Li and Na ions have been discovered. A major goal of this proposal is the identification of new superionic conductors, an aim which will be supported by fundamental studies to identify and control the structural features that most directly influence the ionic conductivity. The development of improved solid state superionic conductors that can replace the organic liquid electrolytes (which are responsible for major flammability, toxicity, and lifetime issues) in current Li-ion battery systems will lead to safer batteries with improved lifetimes. Fundamental studies will be carried out to understand and optimize the conductivity of ions at room temperature within a special CUBICON ceramic host whose cubic symmetry allows ions to be transported equally well in all directions, unlike most other alternative systems. First, chemical syntheses (solid state and ion exchange) will be carried out to prepare a variety of single-phase CUBICON materials of known and novel compositions. Next, X-ray and neutron diffraction studies will be carried out to accurately locate the positions of atoms (enabling both qualitative estimates and quantitative calculations of the strength of bonding and mobility of ions). New in situ methods will be applied to determine ion exchange mechanisms relevant to their synthesis. Finally, physical properties measurements will be done to assess the ionic and electronic conductivity of these materials, and to identify design rules than can be used to prepare CUBICON materials with optimal properties.