Mechanistic Insights into Interface Instability of Sodium Metal Electrodes

Sodium (Na) metal electrodes have generated significant interest due to their low electric potential, high theoretical specific capacity, natural abundance, and cost-effectiveness. However, advancing Na metal battery chemistry with liquid electrolytes requires tackling various interfacial challenges associated with dendrite growth, solid electrolyte interphase (SEI) evolution, and dead metal formation. Understanding the distinct nature of electrochemical, mechanical, and thermal behavior is pivotal to achieving stable Na metal electrode interfaces. This presentation will focus on the coupled electro-chemo-mechanical and transport interactions underlying the reaction heterogeneity and interface instability in Na metal electrodes. The spatio-temporal evolution of heterogeneities at the Na-metal/electrolyte/SEI interface and their influence on mechanistic signatures, such as stress-driven transport, reaction current localization, and the onset of disparate instability modes, will be discussed. The critical role of external pressure and temperature in modulating the transport response, interface morphology, and instability propagation during plating and stripping will be examined.