Redistribution of electronic density in channels of metal–Organic frameworks for high-performance quasi-solid lithium metal batteries

Metal-organic frameworks (MOFs) have attracted intensive interests as solid electrolytes (SEs) due to their talents in facilitating ion transport and chemical tunability. Developing functional MOFs-based conductors with better capacity for ion transport is greatly favored for solid-state batteries (SSBs). Inspired by the function of electron-withdrawing fluorine for both ion transport and regulating solid electrolyte interphase (SEI) formation, herein, we designed and synthesized two Ce-MOFs (Ce-UiO-66-4F and Ce-UiO-66-4Cl) constructed with halogen-decorated ligands. Both the simulated calculation and experimental results show that the exposed -F or -Cl functional groups in pores can regulate the electron-distribution property in channels and promote ions transport, achieving high ionic conductivity (2.16 × 10−4 S cm−1 at room temperature), wide electrochemical window (4.8 V) and lower interfacial impedance. Moreover, such halogen-decorated MOFs can participate the electrochemical formation of SEI and suppress the growth of lithium dendrites. Benefiting from these advantages, the assembled SSBs exhibit high performances even under high-voltage and high-loading conditions. This work thus provides a universal strategy for developing bifunctional MOFs for promoting ion-conductivity and regulating SEI formation.