CAREER: High-Resolution NMR for Paramagnetic Sodium Electrodes

该CAREER项目由材料研究部固态和材料化学项目支持，通过钠基可充电电池的进步，围绕能源可持续性展开，并解决这一挑战的各个方面，从所需的基础材料进步到多样化STEM劳动力的培训。随着需求的持续增长，电池对于确保可靠、可持续和清洁的能源供应至关重要。目前的锂离子电池不能用于长期的、具有成本效益的电网规模的储能，因为它们依赖于钴的供应，而钴受地缘政治不稳定的影响很大。钴的高成本以及锂和镍的成本不断上升是另外令人担忧的问题。美国拥有世界上最大的纯碱储量（钠的主要来源），该研究项目所使用的钠基设备由地球上丰富的锰和铁组成，完全消除了毒性、原材料供应和成本问题。钠基电池的应用受到缺乏可可逆存储大量电荷的正极材料的阻碍。本文在基本结构水平上探索了一类具有高预测能量密度的新型钠阴极材料。对一系列阴极成分的研究，同时使用和开发尖端的核磁共振工具，提供对其工作原理的原子级见解，可能导致发现大规模储能的变革性化学。除了直接的社会影响外，建议的研究活动还可以培养多元化和包容性的劳动力。与该职业奖相关的主要教育工作是：在服务不足的社区开展早期STEM教育和推广，扩大STEM研究的参与，培养有竞争力的STEM劳动力，并使学生成为环境公民。这些目标与美国国家科学基金会的“NSF包括”（NSF INCLUDES）大构想和美国就业计划（American Jobs Plan）一致，后者提出在清洁能源领域创造就业机会，同时解决持续存在的种族不平等问题。本研究项目由材料研究部固态与材料化学项目资助，旨在推进钠（Na）插层化合物的基础科学研究。本研究的总体目标是揭示和控制含有地球丰富过渡金属的webite型Na2MM ‘ f7化合物在M和/或M ’位点上Na （de）嵌入的输运过程和结构变化。这些化合物是基础材料研究的优秀候选者，因为它们的组成多样性，这导致了广泛的和精细可调的化学和物理性质。据推测，控制Na2MM 'F7 Na插入体的局部组成、结构和电荷密度分布是调节其电化学性能的基础。首席研究员和她的研究小组进行了广泛的顺磁核磁共振（NMR）研究和进一步的新发展，通过使用第一性原理统计力学来解释复杂和信息丰富的顺磁核磁共振数据，以实现Ångstrom-scale结构见解。总体目标围绕三个主题：1)了解决定Na2MM 'F7网站的相稳定性和实验可及性的因素；2)揭示了晶体结构和电子结构在Na （de）插层时对Na离子扩散、电子导电性和相稳定性的影响；3)应用第一性原理统计力学方法预测复杂顺磁性固体的有限温度核磁共振性质。除了顺磁核磁共振技术，一套相关的工具将用于提供深入和多尺度的洞察结构，电子和离子传导现象。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。

Part 1: Non-Technical SummaryThis CAREER project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, is centered around energy sustainability through advances in sodium-based rechargeable batteries and address all aspects of this challenge, from the underlying materials advances needed, to the training of a diverse STEM workforce. Batteries are central to securing a reliable, sustainable, and clean energy supply as demand continues to grow. Current lithium-ion batteries cannot be used for long-term, cost-effective grid-scale energy storage as they depend on cobalt supply, which is greatly affected by the geopolitical instability. The high cost of cobalt and rising costs of lithium and nickel are additional concerns. The U.S. holds the world’s largest reserves in soda ash (a major sodium source), and the development of sodium-based devices comprising Earth-abundant manganese and iron, which this research project uses, altogether eliminates issues of toxicity, raw materials supply, and cost. The deployment of sodium-based batteries is hampered by the dearth of cathode materials that store a large amount of charge reversibly. Here, a new class of sodium cathode materials with high predicted energy densities are explored at the fundamental structural level. The study of a range of cathode compositions, while using and developing cutting-edge nuclear magnetic resonance tools that provide atomic-level insights into their working principles, could lead to the discovery of transformative chemistries for large-scale energy storage. Besides direct societal impacts, the proposed research activities to train a plural and inclusive workforce. The main educational efforts tied to this CAREER award are: early STEM education and outreach in underserved communities, broadening participation in STEM research and developing a competitive STEM workforce, and empowering students to become environmental citizens. Such goals align with the NSF’s Big Idea NSF INCLUDES, and the American Jobs Plan that proposes to create employment in Clean Energy and concurrently addresses persistent racial injustice. Part 2 : Technical summaryThis research project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, advances the fundamental science of sodium (Na) intercalation compounds. The overall objective of the proposed research is to reveal and control transport processes and structural changes upon Na (de)intercalation in weberite-type Na2MM’F7 compounds containing Earth-abundant transition metals on the M and/or M’ sites. These compounds are excellent candidates for fundamental materials research because of their compositional variety, which results in wide ranging and finely tunable chemical and physical properties. It is hypothesized that control over the local composition, structure, and charge density distribution of Na2MM’F7 Na intercalation hosts underpin the ability to tune their electrochemical properties. The principal investigator and her research group carry out extensive paramagnetic nuclear magnetic resonance (NMR) studies and further new developments to interpret complex and information-rich paramagnetic NMR data through the use of first-principles statistical mechanics to enable Ångstrom-scale structural insights. The overall objective are structured around three topics: 1) Understand the factors dictating the phase stability and experimental accessibility of Na2MM’F7 weberites; 2) Unravel the role that the crystal and electronic structures play in determining Na-ion diffusion, electronic conductivity and phase stability upon Na (de)intercalation; 3) Apply first-principles statistical mechanics approaches to predict the finite-temperature NMR properties of complex paramagnetic solids. Besides paramagnetic NMR techniques, a suite of relevant tools will be used to provide in-depth and multiscale insights into structural, electronic and ion conduction phenomena.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.