LEAPS-MPS: Probing Solid Electrolyte Interphase of Sodium Metal Anodes Using Plasmonic Effects

NON-TECHNICAL SUMMARY Sodium, similar to lithium, can be used as the electrode material in rechargeable batteries. Sodium is 1,000 times more abundant than lithium, potentially lowering battery costs. Due to its strong reactivity, sodium forms a corrosion film on the surface during battery operation, significantly impacting the performance of batteries. However, the composition and evolution of this corrosion film remain largely unknown. This project, supported by a LEAPS-MPS award, advances our understanding of this corrosion film and lays a firm foundation for developing next-generation sodium-based rechargeable batteries. The project outcomes will broadly impact clean energy technologies and enable a world with zero-carbon emissions. The educational outreach targets diverse engagement, focusing on female and underrepresented students in STEM fields. The activities include integrating research into the curriculum and electrification certificate programs, hosting undergraduate research in the lab, and engaging K-12 students in electrochemistry, especially Girls in Science and Engineering and minority students. The educational plan educates students at all levels about research areas at the intersection of materials, electrochemistry, microscopy, and spectroscopy. TECHNICAL SUMMARY Sodium (Na) is a compelling anode material due to its low electrochemical potential, high specific capacity, and natural abundance. Due to its strong reducing property, Na forms a corrosion film – solid electrolyte interphase (SEI) on the surface, impacting battery performances such as cyclability, capacity retention, rate capability, and safety. The understanding of the SEI is challenged by its complex composition, dependence on electrolyte and temperature, thin thickness (several to tens of nanometers), sensitivity to ambient conditions, and its constant evolution in a closed system. This fundamental research project, supported by a LEAPS-MPS award, elucidates the composition and evolution of Na SEI by using in-situ and non-invasive Raman spectroscopy enhanced by Na metal nanostructures, bridging interdisciplinary fields of electrochemistry and nanophotonics. Specifically, researchers at Oakland University focus on (1) probing Na SEI as a function of electrolytes using a Na Moiré metasurface and (2) in situ probing Na SEI using Na metal microparticles and nanoparticles. The technical approaches for the research include plasmonic Na metasurfaces for surface-enhanced Raman spectroscopy (SERS), a microelectrodes-based Na particle synthesis and characterization platform, and in situ and operando Raman spectroscopy coupled with a temperature stage. The expected outcomes of this project will advance the fundamental knowledge of Na SEI, providing insights into crucial SEI-electrolyte and SEI-temperature relationships. 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.