Surface energy-driven electrodeposition stability in sodium metal electrodes

Abstract Dendrite growth arising from interfacial instability remains a major obstacle to the advancement and commercialization of metal anode-based batteries. Sodium metal batteries (SMBs), a promising alternative to lithium (Li)-based systems due to the broad availability and lower cost of sodium (Na), suffer from pronounced interfacial instabilities during plating. A principal modulating factor influencing the propensity for dendritic growth in metal anodes is the interfacial surface energy at the active metal-electrolyte interface. This work explores the role of surface energy-induced interfacial instability in SMBs employing liquid electrolytes. It is shown that higher interfacial energies promote a more uniform deposition front, thereby reducing the tendency for uneven electrodeposition. For low interfacial energies, the reduced energetic penalty for creating new surfaces promotes rapid tip growth and branching, leading to highly unstable deposition morphologies with pronounced dendritic features. Furthermore, a comparative analysis between Li and Na metal anodes reveals that intrinsic differences in the material properties significantly influence electrodeposition stability. Through a combination of qualitative visualization and quantitative analysis, this study provides a comprehensive understanding of the role of surface energy in dictating interface evolution in SMBs, offering insights for the rational design of stable metal anode systems.