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

全固态可充电电池具有能量密度高、成本低、安全性高等优点。因此，它们被认为是电动汽车的下一代电池技术，有望满足对更安全、更紧凑、更大容量储能设备的其他关键需求。但功率密度低、长期稳定性差，限制了其实际应用和市场竞争力。这项研究由美国国家科学基金会材料研究部固态和材料化学项目资助，使用新的核磁共振和核磁共振技术为这些限制的原因提供了新的见解，并有助于开发高性能固态可充电电池。它还产生了新的知识，促进了对基本界面化学的深入理解，而瓶颈在于提高其他技术的性能，包括燃料电池、超级电容器和太阳能电池。作为该项目的一部分，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，而且可能有益于生物医学研究。此外，主要研究者积极从HBCU机构招募学生，并让女性和少数民族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。旨在吸引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。技术总结：在电极-固体电解质界面处，质量和能量传输的大阻力阻碍了高性能固态可充电电池的成功。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固态和材料化学项目资助，采用示踪交换核磁共振方法探测离子通过电极-固体电解质界面的传输，用高分辨率深度剖面磁共振成像（MRI）量化Li缺乏症，并用电化学阻抗谱确定在原位和原位条件下的界面电阻。这项研究提供了限制离子在界面上传输的关键因素的见解，这有助于界面设计以最小的界面阻抗实现最佳的电极-电解质相容性。研究人员建立了Li缺乏、扩散和界面电阻之间的实时相关性。选择Li/Li7La3ZrO12/Li和Li/Li10GeP2S12/Li两种模型体系，是因为它们具有氧化物和硫化物电解质的代表性，以及它们在Li电极-固体电解质界面上的明显差异。在实验研究的基础上，建立了一个分析模型，定量地阐明了锂缺乏和扩散对界面阻抗的影响。该模型在RandFlux软件中实现，用于预测全固态可充电电池的电化学过程和性能。在这个项目中，主要研究者积极地从HBCU机构招募学生，并让女性和少数民族学生参与正在进行的研究。旨在吸引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。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.