(Invited) SEI or Solvation Structure: What Determines Electrode Stability in Rechargeable Batteries?

Solid-electrolyte interphase (SEI) chemistry has garnered significant research interest in the past two decades because of its positive effect on boosting electrode performance in rechargeable batteries. Herein, we present a new viewpoint based on metal ion solvation structure and molecular-scale interfacial model on electrode surface, which could compliment exiting knowledge about the SEI effect. We show that the observed variation in de-solvation behavior of mobile ions also depends on their solvation structure, which is determined by multiple factors (e.g., cations, solvents, anions, and additives present in the electrolyte). The presented interfacial model can predict the experimentally-observed electrode performance (e.g., graphite, alloying, metal anode, and cathode) in different types of electrolytes. Our model can predict electrode performance through the proposed cation-solvent interactions and de-solvation behaviors, and can be used as basis to develop new types of electrolytes for mobile (ion) batteries.