Diametric Extremes in the Ionic Conductivity of Mixed Glass Former Solid Electrolytes

太阳是一种巨大的未开发能源，它有一个昼夜循环的模式。 因此，需要能量存储系统，并且如果能够解决安全性、高成本和低效率的问题，则电池是正在考虑的有前途的技术。考虑到所需能量存储系统的大小，正在积极研究非常低成本和地球丰富的钠电池。然而，今天的钠电池必须在300 ℃下工作，因为电池隔板（固体电解质）具有低Na+离子电导率，这导致这种电池效率低、不安全且昂贵。由于这些原因，重要的是更好地理解Na+离子在固态中的运动，以便可以开发更新的更好的导电固体电解质。在这个项目中，正在研究新的玻璃态固体电解质，可以非常便宜地制造高Na+离子电导率。 特别是，马丁的研究小组正在研究基于两种网络形成剂的新型三元玻璃（例如，硅、硼或锗），其形成高度交联的化学键排列。 正在研究这些特定的玻璃，因为已经发现，在两种玻璃形成剂的某些组合中，Na+离子传导显著增加，而对于其他组合，Na+离子运动显著降低。通过研究这两种不同的系统及其相反的行为，将有可能更多地了解Na+离子如何通过固体进行传导，并有助于开发基于更好的固体电解质的新型钠电池。技术方案当优化化学性质时，掺杂到玻璃形成体中的Na+离子可具有非常高的电导率。玻璃态固体电解质的高离子电导率和改进的物理和电化学性质的罕见的一致性可以通过例如以恒定的Na+分数混合两种玻璃形成剂B和P来获得。这种基于地球丰富的Na的优化的混合玻璃形成物玻璃状固体电解质可以是可以制造下一代更便宜、更安全和更有效的大型电网规模电池的候选物。虽然Na B P O混合玻璃形成剂系统表现出积极的效果，但新的研究也发现了显示出前所未有的负面影响的系统。在硫化物玻璃中也观察到这种双重作用。在这里，B添加到Na P S玻璃指数增加的离子电导率，而Ge添加到相同的玻璃降低其离子电导率。虽然在理解固体电解质中的离子传导方面取得了进展，但仍然存在重大的知识差距。 在进行这项研究时，两名博士研究生和一名本科生将制备和表征新的混合玻璃前体玻璃，其表现出这些相反的混合玻璃前体效应。通过这项研究，他们将开发先进的实验室为基础的研究技能，材料科学，玻璃研究和固态电化学。他们还将通过与德国领先的玻璃理论和模拟研究小组的国际合作来发展计算技能和知识，他们将在那里度过为期10周的夏季研究经验，学习分子动力学和反向蒙特卡罗模拟技术。

NON-TECHNICAL DESCRIPTIONThe sun, a very large source of untapped energy, has a cyclic pattern of night and day. Therefore, energy storage systems are required and batteries are promising technologies being considered if problems of safety, high cost, and low efficiency can be resolved. Given the size of energy storage systems required, very low cost and earth abundant sodium batteries are being actively researched. Sodium batteries today, however, must operate at 300 C because the battery separator, a solid electrolyte, has a low Na+ ion conductivity and this causes such batteries to be inefficient, unsafe, and expensive. For these reasons, it is important to better understand Na+ ion motion in the solid state so that newer better conducting solid electrolytes can be developed. In this project, new glassy solid electrolytes are being studied that can be made very inexpensively with high Na+ ion conductivities. In particular, Martin's group is examining new ternary glasses based upon two network formers (e.g., silicon, boron, or germanium) that form a highly cross-linked arrangement of chemical bonds. These particular glasses are being studied because it has been found that in some combinations of two glass formers the Na+ ion conduction increases dramatically whereas for other combinations the Na+ ion motion decreases significantly. By studying these two different systems and their opposite behaviors, it will be possible to learn more about how Na+ ions conduct through solids and help develop new sodium batteries based upon better solid electrolytes. TECHNICAL DETAILSNa+ ions doped into a glass former can have very high conductivities when the chemistry is optimized. A rare coincidence of high ionic conductivity and improved physical and electrochemical properties of glassy solid electrolytes can be obtained by mixing two glass formers, B and P, for example, at a constant fraction of Na+. Such optimized mixed glass former glassy solid electrolytes based upon earth abundant Na may be candidates from which next generation cheaper, safer, and more efficient large grid-scale batteries can be made. While the Na B P O mixed glass former system exhibits a positive effect, new research has also discovered systems that show never before seen negative effects. This dual behavior of the effects is also observed in sulfide glasses. Here, B additions to a Na P S glass exponentially increase the ionic conductivity, whereas Ge additions to the same glass decrease its ionic conductivity. While progress has been made in understanding ionic conduction in solid electrolytes, significant knowledge gaps still exist. In undertaking this research, two doctoral graduate students and one undergraduate student will prepare and characterize new mixed glass former glasses that exhibit these opposite mixed glass former effects. Through this research, they will develop advanced laboratory-based research skills in materials science, glass research, and solid state electrochemistry. They will also develop computational skills and knowledge through an international collaboration with a leading glass theory and simulation research group in Germany where they will spend a 10-week summer research experience learning molecular dynamics and reverse Monte Carlo simulation techniques.