High Ionic Conductivity Motivated by Multiple Ion‐Transport Channels in 2D MOF‐Based Lithium Solid State Battery

Abstract Metal‐organic frameworks (MOFs) have been proposed as novel fillers for constructing polymer solid electrolytes based composite electrolytes. However, MOFs are generally used as passive fillers, in‐depth revealing the binding mode between MOFs and polyethylene oxide (PEO), the critical role of MOFs in facilitating Li + transport in solid electrolytes is full of challenges. Herein, inspired by density functional theory (DFT) the 2D‐MOF with rich unsaturated metal coordination sites that can bind the O atom in PEO through the metal–oxygen bond, anchor TFSI − to release Li + , resulting in a remarkable Li + transference number of 0.58, is reported according well with the experimental results and molecular dynamics (MD) simulation. Impressively, after the introduction of the 2D‐MOF, the Li + can rapidly hop along the benzene ring center within the 2D‐MOF plane, and the interface between the benzene ring and PEO can also serve as a fast Li + migration pathway, delivering multiple ion‐transport channels, which present a high ion conductivity of 4.6 × 10 −5 S cm −1 (25 °C). The lithium symmetric battery is stable for 1300 h at 60 °C, 0.1 mA cm −2 . The assembled lithium metal solid state battery maintains high capacity of 162.8 mAh g −1 after 500 cycles at 60 °C and 0.5 C. This multiple ion‐transport channels approach brings new ideas for designing advanced solid electrolytes.