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

Abstract 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 (LiFePO 4 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.