(Invited) Stabilizing Graphite Anode in Electrolytes with Micelle-Like Nanostructures for High-Rate Lithium Storage

Abstract

Graphite stands out as the preferred anode material in commercial lithium-ion batteries (LIBs). However, its limited compatibility with diverse solvent molecules poses a significant challenge in selecting electrolyte solvents for LIBs. The issue arises from the co-intercalation of solvent molecules into the graphite layer alongside Li ions, resulting in layer exfoliation. This constraint has left few alternatives, primarily relying on ethylene carbonate (EC)-based mixed solvents. Consequently, the translation of electrolyte advancements from the past three decades into practical LIBs has been hindered. In this study, we present electrolytes exhibiting a micelle-like structure designed at nanoscale to impede the liquid-phase exfoliation of the graphite layer. The micelle-like electrolyte structure, derived from concentrated long-chain lithium salts, effectively segregates Li ions from free diethylene carbonate (DOL) solvent molecules. This segregation mitigates interactions between graphite particles and free solvent molecules during Li intercalation. Our proposed mechanism provides refreshed insights, highlighting the significance of the concentrated long-chain lithium salts (LiTFSI) for the graphite stability rather than the widely accepted Li coordination structure or solid electrolyte interphase. These findings offer a pivotal guideline for enhancing LIB performance by overcoming electrolyte limitations on graphite anodes.