Porous Aromatic Frameworks Filler with Anion‐Constrained Centers in Composite Polymer Electrolyte for Lithium‐Ion Batteries

Abstract The widespread use of lithium‐ion batteries (LIBs) based on solid polymer electrolytes (SPEs) is hindered by their low Li + conductivity and safety risks posed by the growth of lithium dendrites. To overcome the aforementioned challenges, we designed a cationic porous aromatic framework (PAF‐142) and introduced it as a filler into SPEs to obtain a composite polymer electrolyte (CPE), PAF‐142‐CPE. The cationic imidazolium sites could effectively constrain the movement of anions through electrostatic interactions. Furthermore, the design of the imidazolium‐based building units allowed the cationic sites to be located within the framework, which promoted the transport of Li + . Density functional theory (DFT) and molecular dynamics simulations revealed the mechanism by which PAF‐142 promoted the dissociation of lithium salts and enhanced Li + transport. Benefiting from these advantages, the Li + conductivity of quasi‐solid composite polymer electrolyte (QCPE), PAF‐142‐QCPE reached 8.77 × 10 −4 S cm −1 at 20 °C. Additionally, a stable interface with abundant inorganic components was formed between PAF‐142‐QCPE and the lithium electrode, thus effectively inhibiting the growth of lithium dendrites, thereby achieving stable long cycle of the Li//PAF‐142‐QCPE//Li cell for more than 8500 h. The Li//PAF‐142‐QCPE//LFP cell demonstrated excellent cycle life exceeding 1400 cycles. This study proposes a promising SPEs performance‐enhancing solution, advancing cutting‐edge lithium‐ion batteries.