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

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.