CAREER: NMR of the Solid Electrolyte Interphase on Li Metal Anodes

金属锂电池有望在电气化交通和电网存储中实现高能量密度应用。然而，锂金属元件存在严重的界面不稳定性，导致效率损失和严重的安全问题。在负极和液体电解液之间的区域，由于电解液化合物的自发击穿而产生固体电解质界面(SEI)。金属锂电池中的SEI被认为在锂沉积过程中起着关键作用，但用传统的材料表征方法进行评估是具有挑战性的。在这项提议中，我们使用核磁共振(核磁共振)光谱技术来创建分子水平的描述，以描述发生在锂金属界面的化学反应，最终缓解形成微结构，从而实现安全高效的电池运行。这一研究计划与教育活动紧密结合，通过针对当地研究人员和行业合作伙伴的实践“能源材料原位核磁共振”研讨会，弥合核磁共振培训方面的差距。与这些努力相辅相成的是，计划通过与Barnard(女子学院)的科学途径学者方案合作，扩大任职人数不足和处境不利的妇女参与本科生研究的范围。我们将利用社区内部的联系举办一次TEDx会议，以改善对普通公众的核磁共振教育，并通过强调核磁共振在疫苗开发、能量储存、疾病治疗和艺术方面的应用，为有抱负的年轻人及其家庭带来兴奋。这项建议的目的是利用核磁共振光谱学来阐明SEI形成和功能的化学机制，并利用这些知识在锂金属电池中实现所需的平滑锂沉积。获得这一信息的关键挑战是复杂的SEI结构在Li沉积/溶解过程中演变，并且当从其原始操作环境中移除时很容易受到干扰。为了克服这些问题，我们建议使用溶液和固态核磁共振相结合的方法，结合磁共振成像(MRI)来全面评估形成在锂金属阳极表面的SEI的组成、排列和动力学。原位核磁共振/磁共振成像提供了关于多相界面现象的准确的化学、空间和时间信息，以阐明电解液分解、阳极/阴极串扰和离子传输对锂沉积行为的作用。指定界面化学和输运现象决定了电化学非活性锂的形成，这将使我们能够在分子水平上描述支撑低库仑效率的化学机制。我们还将教育学生和工业研究人员使用具有成本效益的电极制造技术和广泛可用的电化学和核磁共振设备的原位核磁共振方法，以便他们能够超越当前收集和分析数据的“黑箱”方法。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。

Lithium metal batteries are expected to enable high energy density applications in electrified transportation and grid storage. However, lithium metal components suffer from severe interfacial instabilities, leading to efficiency losses and serious safety concerns. In the region between the negative electrode and the liquid electrolyte, a solid electrolyte interphase (SEI) is produced by the spontaneous breakdown of electrolyte compounds. The SEI in lithium metal batteries is hypothesized to play a key role in lithium deposition but is challenging to assess with traditional materials characterization methods. In this proposal, we use nuclear magnetic resonance (NMR) spectroscopic techniques to create a molecular-level description of the chemical reactions that occur at lithium metal interfaces to ultimately mitigate the formation microstructures for safe and efficient battery operation. This research program is strongly coupled with educational activities to bridge gaps in NMR training through a hands-on “In Situ NMR of Energy Materials” workshop aimed at local researchers and industry partners. These efforts are complemented with plans to broaden the participation of underrepresented and underprivileged women in undergraduate research through a partnership with the Science Pathways Scholars Program at Barnard (women's college). We will leverage connections within the community to host a TEDx conference to improve NMR education for the general public and generate excitement for aspiring youth and their families by highlighting the use of NMR for vaccine development, energy storage, disease treatment, and the arts.The objective of this proposal is to use NMR spectroscopy to elucidate the chemical mechanisms underpinning SEI formation and function, and to use that knowledge to achieve the desired smooth Li deposition in Li metal batteries. The key challenge in obtaining this information is that the complex SEI structure evolves during Li deposition/dissolution and is easily disturbed when removed from its native operating environment. In order to overcome these issues, we propose to use a combination of solution and solid-state NMR, together with magnetic resonance imaging (MRI) to provide a comprehensive assessment of the composition, arrangement, and dynamics of the SEI that forms on the surface of Li metal anodes. In situ NMR/MRI provides accurate chemical, spatial, and temporal information on multiphase interfacial phenomena to elucidate the role of electrolyte decomposition, anode/cathode crosstalk, and ion transport on lithium deposition behavior. Assignment of the interfacial chemistries and transport phenomena that dictate the formation of electrochemically inactive Li will allow us to describe, at the molecular-level, chemical mechanisms underpinning low Coulombic efficiency. We will also educate students and industrial researchers on in situ NMR methods using cost-effective electrode fabrication techniques and widely available electrochemical and NMR equipment so that they can go beyond current, “black box” approaches to collect and analyze data.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.