Regulating Anode‐Electrolyte Interphasial Reactions by Zwitterionic Binder Chemistry in Lithium‐Ion Batteries with High‐Nickel Layered Oxide Cathodes and Silicon‐Graphite Anodes

Abstract

AbstractThe practical application of silicon (Si)‐based anodes faces challenges due to severe structural and interphasial degradations. These challenges are exacerbated in lithium‐ion batteries (LIBs) employing Si‐based anodes with high‐nickel layered oxide cathodes, as significant transition‐metal crossover catalyzes serious parasitic side reactions, leading to faster cell failure. While enhancing the mechanical properties of polymer binders has been acknowledged as an effective means of improving solid‐electrolyte interphase (SEI) stability on Si‐based anodes, an in‐depth understanding of how the binder chemistry influences the SEI is lacking. Herein, a zwitterionic binder with an ability to manipulate the chemical composition and spatial distribution of the SEI layer is designed for Si‐based anodes. It is evidenced that the electrically charged microenvironment created by the zwitterionic species alters the solvation environment on the Si‐based anode, featuring rich anions and weakened Li+‐solvent interactions. Such a binder‐regulated solvation environment induces a thin, uniform, robust SEI on Si‐based anodes, which is found to be the key to withstanding transition‐metal deposition and minimizing their detrimental impact on catalyzing electrolyte decomposition and devitalizing bulk Si. As a result, albeit possessing comparable mechanical properties to those of commercial binders, the zwitterionic binder enables superior cycling performances in high‐energy‐density LIBs under demanding operating conditions.