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Electrolyte engineering is crucial for improving cathode electrolyte interphase (CEI) to enhance the performance of lithium‐ion batteries, especially at high charging cut‐off voltages. However, typical electrolyte modification strategies always focus on the solvation structure in the bulk region, but consistently neglect the dynamic evolution of electrolyte solvation configuration at the cathode‐electrolyte interface, which directly influences the CEI construction. Herein, we reveal an anti‐synergy effect between Li+‐solvation and interfacial electric field by visualizing the dynamic evolution of electrolyte solvation configuration at the cathode‐electrolyte interface, which determines the concentration of interfacial solvated‐Li+. The Li+ solvation in the charging process facilitates the construction of a concentrated (Li+‐solvent/anion‐rich) interface and anion‐derived CEI, while the repulsive force derived from interfacial electric field induces the formation of a diluted (solvent‐rich) interface and solvent‐derived CEI. Modifying the electrochemical protocols and electrolyte formulation, we regulate the "inflection voltage" arising from the anti‐synergy effect and prolong the lifetime of the concentrated interface, which further improves the functionality of CEI architecture. [ABSTRACT FROM AUTHOR]

Acting as a passive protective layer, solid‐electrolyte interphase (SEI) plays a crucial role in maintaining the stability of the Li‐metal anode. Derived from the reductive decomposition of electrolytes (e.g. anion and solvent), the SEI construction presents as an interfacial process accompanied by the dynamic de‐solvation process during Li‐metal plating. However, typical electrolyte engineering and related SEI modification strategies always ignore the dynamic evolution of electrolyte configuration at the Li/electrolyte interface, which essentially determines the SEI architecture. Herein, by employing advanced electrochemical in situ FT‐IR and MRI technologies, we directly visualize the dynamic variations of solvation environments involving Li+‐solvent/anion. Remarkably, a weakened Li+‐solvent interaction and anion‐lean interfacial electrolyte configuration have been synchronously revealed, which is difficult for the fabrication of anion‐derived SEI layer. Moreover, as a simple electrochemical regulation strategy, pulse protocol was introduced to effectively restore the interfacial anion concentration, resulting in an enhanced LiF‐rich SEI layer and improved Li‐metal plating/stripping reversibility. [ABSTRACT FROM AUTHOR]