Regulating Dynamic Evolution of Interfacial Electrolyte Configuration via Inert Cation Induced Anion Anchoring to Stabilize Lithium‐Metal Anode

Interfacial stability in high-energy-density lithium metal batteries (LMBs) hinges on precise regulation of dynamic interfacial electrolyte configuration. Although inert cations are frequently employed to stabilize Li-metal anode, their interfacial adsorption behavior and the resultant evolution of the electrolyte/electrode interface remain elusive. Herein, using in-situ spectroscopy, we visualized the adsorption of inert cations, exemplified by tetrabutylammonium (TBA⁺). Furthermore, the inherent anion-lean, solvent-rich interface formed during desolvation was mitigated by the electrostatic interaction between TBA⁺ and anions. This anion-anchoring effect promotes preferential anion decomposition, thereby suppressing parasitic reactions associated with solvent decomposition. Consequently, the cycling stability and reversibility of Li stripping/plating are significantly enhanced. This work not only refreshes the understanding of inert cations on regulating the interfacial electrolyte configuration, but also highlights the close relationship between the interfacial solvation configuration and the SEI architecture, offering fundamental insights for potential electrolyte design.