Correlations of Li Deficiency, Diffusion, and Interfacial Impedance in Solid-State Batteries Probed by In Situ Tracer Exchange NMR and Depth-Profiling MRI Combined with Modeling

非技术总结全固态充电电池具有高能量密度、低成本和更高的安全性。因此，它们被认为是电动汽车的下一代电池技术，并有望满足对更安全、更紧凑和更大容量的储能设备的其他关键需求。然而，低功率密度和较差的长期稳定性限制了其实际应用和市场竞争力。这项研究由NSF材料研究部的固态和材料化学计划资助，使用新的核磁共振和核磁共振技术来提供对这些限制原因的新见解，并有助于开发高性能固态充电电池。它还产生了新的知识，促进了对基本界面化学的深入理解，而基础界面化学是提高燃料电池、超级电容器和太阳能电池等其他技术性能的瓶颈。作为该项目的一部分开发的新的核磁共振和核磁共振方法不仅有助于发现用于技术应用的新型功能材料，还可能有助于生物医学研究。此外，首席调查员积极从HBCU机构招募学生，并让妇女和少数族裔学生参与正在进行的研究，从而教育和培训多样化的下一代STEM研究人员。旨在让公众参与科学讨论的推广活动包括开发一款名为“核磁共振之声”的应用程序。技术总结电极-固体电解液界面的质量和能量传输阻力太大，阻碍了高性能固态充电电池的成功。了解锂离子在这些界面上的扩散及其与界面结构和组成的关系，对于解决与界面阻抗相关的挑战至关重要。该项目由美国国家科学基金会材料研究部的固态和材料化学计划资助，利用示踪交换核磁共振方法探测电极-固体电解质界面上的离子传输，用高分辨率深度剖面磁共振成像(MRI)定量锂缺乏，并在EX和现场条件下用电化学阻抗谱测定界面电阻。这项研究提供了对限制离子在界面上传输的关键因素的洞察，有助于界面设计以最小的界面阻抗实现最佳的电极-电解液兼容性。研究人员建立了锂缺乏、扩散和界面阻力之间的实时关联。选择了Li/Li_7La_3ZrO_(12)/Li和Li/Li10GeP_2S_(12)/Li两个模型体系，考察了它们对氧化物和硫化物电解液的代表性，以及它们在Li电极-固体电解液界面上的明显差异。在实验研究的基础上，建立了一个分析模型，定量地解释了Li的缺乏和扩散对界面阻抗的影响。该模型在RandFlux软件中实现，用于预测全固态充电电池的电化学过程和性能。在这个项目中，首席调查员积极从HBCU机构招募学生，并让妇女和少数族裔学生参与正在进行的研究。旨在让公众参与科学讨论的外展活动包括开发名为“核磁共振之声”的应用程序。该奖项反映了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 rechargeable batteries promise high energy density, low cost, and improved safety. Therefore, they are considered as the next-generation battery technology for electric vehicles and expected to meet other critical needs for safer, more compact, and higher-capacity energy storage devices. However, low power density and poor long-term stability limit their practical applications and market competitiveness. This research, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, uses new NMR and MRI techniques to provide new insights into the cause of these limitations and helps to develop high-performance solid-state rechargeable batteries. It also generates new knowledge that promotes in-depth understanding of fundamental interface chemistry, where the bottleneck lies for improved performance of other technologies including fuel cells, super-capacitors, and solar cells. The new NMR and MRI methodologies developed as part of this project not only facilitate the discovery of novel functional materials for technological applications, but might also benefit biomedical research. Additionally, the principle investigator actively recruits students from a HBCU institution and engages women and minority students in the ongoing research, thereby educating and training a diverse next generation of STEM researchers. Outreach activities aimed at engaging the general public in scientific discussions include the development of an app with the title "The Sound of NMR".TECHNICAL SUMMARYLarge resistance for mass and energy transport at electrode-solid electrolyte interfaces impedes the success of high-performance solid-state rechargeable batteries. Understanding Li-ion diffusion across these interfaces and its relationships with structures and compositions of interfaces is critical to addressing the challenges associated with interfacial impedance. This project, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, probes ion transport through electrode-solid electrolyte interfaces by employing the tracer-exchange NMR method, to quantify Li deficiency with high-resolution depth-profiling magnetic resonance imaging (MRI), and determines interfacial resistance with electrochemical impedance spectroscopy, under both ex and in situ conditions. This study provides insight into the critical factors that limit ion transport at the interfaces, which aids interface design for optimal electrode-electrolyte compatibility with minimized interfacial impedance. The researchers establish real time correlations among Li deficiency, diffusion, and interfacial resistance. Two model systems, Li/Li7La3ZrO12/Li and Li/Li10GeP2S12/Li, are chosen for their representativeness of oxide and sulfide electrolytes and their distinct differences at the Li electrode-solid electrolyte interfaces. Based on the experimental investigation, an analytical model is developed to quantitatively elucidate the impact of Li deficiency and diffusion on interfacial impedance. This model is implemented in the RandFlux software, for predicting the electrochemical processes and performance of all-solid-state rechargeable batteries. For this project, the principle investigator actively recruits students from a HBCU institution and engages women and minority students in the ongoing research. Outreach activities aimed at engaging the general public in scientific discussions include the development of an app with the title "The Sound of NMR".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.