CAREER: High-Resolution NMR for Paramagnetic Sodium Electrodes

Part 1: Non-Technical Summary

This 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 summary

This 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.