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

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 x 10(-5) S cm(-1) (25 & DEG;C). The lithium symmetric battery is stable for 1300 h at 60 & DEG;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 & DEG;C and 0.5 C. This multiple ion-transport channels approach brings new ideas for designing advanced solid electrolytes.