Electric‐Dipole Coupling Ion‐Dipole Engineering Induced Rational Solvation‐Desolvation Behavior for Constructing Stable Solid‐State Lithium Metal Batteries

Solid-state polymer electrolytes (SPEs) with high ionic conductivity, a wide voltage window, and an ultrastability electrolyte/electrode interface are essential for practical applications of solid lithium-metal batteries but particularly challenging. The key to overcoming these long-term obstacles lies in the rational design of the Li⁺ solvation-desolvation behavior in SPEs. Herein, we propose an electric-dipole coupling ion-dipole strategy to modulate the Li⁺ solvation structure and enhance Li⁺ desolvation kinetics. The experimental characterizations and theoretical calculations indicate that the free solvents and FSI^- are anchored by ion-dipole interactions, which facilitate the transfer of Li⁺ and obtain a wide electrochemical stability window. Coupling the electric-dipole interactions that promote lithium salt dissociation and rapid ion desolvation contributes to obtaining more mobile Li⁺ and realizing an inorganic-rich electrolyte/electrode interface. Benefiting from the above benefits, the assembled lithium symmetric cells and the full cells demonstrate ultralong cycling life. More importantly, full cells with high-loading cathodes (LiFePO₄ with 11.25 mg cm^-2, NCM811 with 7.84 mg cm^-2) and pouch cell still display stable cycling. This research gives valuable insights into regulating the solvation-desolvation behavior in SPEs and facilitates the development of state-of-the-art Li metal batteries.