REPiB

Battery performance is closely tied to the physicochemical processes occurring at the active material/electrolyte interfaces. In Li-ion batteries, the solid electrolyte interface (SEI) formed by reductive decomposition of the electrolyte has long been recognized as critical for the cycling stability and efficiency. However, recent studies have underscored the key role of cation solvation in concentrated electrolytes (both in Li-ion batteries and beyond) and its impact on electrode potential, making it possible to bypass the competitive reductive processes like SEI formation and improve performance. These new insights are driving a paradigm shift in electrolyte design, both for non-aqueous as well as aqueous batteries. Despite these advances, no mechanistic electrochemical model currently exists to account for the coupling between solvation and electron transfer at the interface in highly concentrated electrolytes, nor does satisfactorily explain the strong deviation of the electrode potential from the standard Nernst equation. The ambition of the REPiB project is to fill this gap by developing a generic electrochemical model applicable across various battery types, integrating desolvation and ion insertion (or electrodeposition) at the active material/electrolyte interface, and allowing to rationalize the electrode potential. This fundamental research project relies on a comprehensive approach, combining and confronting experimentation, mechanistic modeling, electrochemical simulations, and theoretical calculations. It also extends to practical implementation through the rational development of electrolytes for optimized batteries, up to the cell level.