Understanding the Key to Unlocking Fast Li-ion Conduction in Fluoride-based Solid Electrolytes

非技术总结所有固态电池都有可能将液体电池的能量密度提高30%。不幸的是，目前它们在界面处遭受化学降解，锂在经常用作电解液的氧化物颗粒之间沉积，这最终阻碍了它们的长期可逆性。这项工作的目标是在材料研究部陶瓷项目的支持下，开发更坚固的氟化物材料，以抵御这些有害的副反应。虽然氟化物过去一直被用作固体电解质，但很少有人发现在室温下具有快速离子导电性的相。这项工作假定缺陷的形成能对快速扩散起关键作用，并试图阐明在合成过程中控制缺陷演化的方法。技术总结本项目将研究新的氟化物石榴石和锆基化合物，以更好地了解氟化物的结构刚性如何影响离子导电性。电化学阻抗谱和密度泛函理论(DFT)的计算将被用来更深入地理解电荷通过弱极化的氟化物阴离子亚晶格的输运。将进行异价化学取代，以考察增加锂含量或在晶格中产生空位对导电性的影响。从根本上说，这项拟议的研究旨在通过一种涉及合成、高级表征和理论建模的综合方法，加深对如何促进基于氟化物的固体电解质中的快速离子传输的理解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYAll-solid-state batteries have the potential to increase the energy density of liquid-based cells by 30%. Unfortunately, they currently suffer from chemical degradation at the interfaces and deposition of Li between particles of the oxides frequently used as the electrolyte, which ultimately hinders their long-term reversibility. The goal of this work, supported by the Ceramics Program within the Division of Materials Research, is to develop fluoride-based materials that are more robust against these detrimental side reactions. While fluorides have been explored as solid electrolytes in the past, very few phases with fast ionic conductivity at room temperature have been discovered. This work postulates that the formation energy of defects plays a critical role for enabling fast diffusion and seeks to elucidate ways to control their evolution during synthesis. TECHNICAL SUMMARYThis project will study new fluoride-based garnets and Zr-based compounds to better understand how the structural rigidity of fluorides affects ionic conductivity. Electrochemical impedance spectroscopy and Density Functional Theory (DFT) calculations will be used to gain a deeper understanding of charge transport through the weakly polarizable anionic sublattice of fluorides. Aliovalent chemical substitutions will be performed to examine the impact of increasing the lithium content or creating vacancies in the lattice has on the conductivity. Fundamentally, the proposed research seeks to develop a deeper understanding of how to promote fast ion transport in fluoride-based solid electrolytes through an integrated approach involving synthesis, advanced characterization, and theoretical modeling.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.