5.1 µm Ion‐Regulated Rigid Quasi‐Solid Electrolyte Constructed by Bridging Fast Li‐Ion Transfer Channels for Lithium Metal Batteries

Abstract An ultra‐thin quasi‐solid electrolyte (QSE) with dendrite‐inhibiting properties is a requirement for achieving high energy density quasi‐solid lithium metal batteries (LMBs). Here, a 5.1 µm rigid QSE layer is directly designed on the cathode, in which Kevlar (poly(p‐phenylene terephthalate)) nanofibers (KANFs) with negatively charged groups bridging metal‐organic framework (MOF) particles are served as a rigid skeleton, and non‐flammable deep eutectic solvent is selected to be encapsulated into the MOF channels, combined with in situ polymerization to complete safe electrolyte system with high rigidness and stability. The QSE with constructed topological network demonstrates high rigidity (5.4 GPa), high ionic conductivity (0.73 mS cm⁻¹ at room temperature), good ion‐regulated properties, and improved structural stability, contributing to homogenized Li‐ion flux, excellent dendrite suppression, and prolonged cyclic performance for LMB. Additionally, ion regulation influences the Li deposition behavior, exhibiting a uniform morphology on the Li‐metal surface after cycling. According to density‐functional theory, KANFs bridging MOFs as hosts play a vital function in the free‐state and fast diffusion dynamics of Li‐ions. This work provides an effective strategy for constructing ultrathin robust electrolytes with a novel ionic conduction mode.