Quasi -Solid -State Composite Electrolytes with Multifunctional 2D Molecular Brush Fillers for Long-Cycling Lithium Metal Batteriest

The ever-growing demand for next-generation high -energy-density devices drives the development of lithium metal batteries with enough safety and high performance, in which quasi -solid-state composite electrolytes (QSCEs) with high ionic conductivity and lithium ion transference number (t(Li+)) are highly desirable. Herein, we successfully synthesize a kind of two-dimensional (2D) molecular brush (GO-g-PFIL) via grafting poly(ionic liquid) side-chain (poly(3-(3,3,4,4,4-pentafluorobutyl)-1-vinyl-1H-imidazol-3-ium bis(trifluoromethanesulfonyl)imide), denoted as PFIL) on the surface of 2D graphene oxide (GO) sheet. GO-g-PFIL is used as multifunctional filler to prepare novel composite membranes and corresponding QSCEs (e.g., QSCE-PH/GPFIL3/P). The as -obtained QSCE-P1-1/GPFIL3/P integrates features of PFIL side-chain -enhanced lithium ion conduction, poly(vinylidene fluoride-co-hexafluoropropene) backbone -induced flexibility, and GO-strengthened mechanical property. As a result, our ultrathin (21 tim) self-supporting QSCE-P1-1/GPFIL3/P exhibits high ionic conductivity (3.24 x 10(-4) S"CM-1) and excellent tLj+ (0.82) at room temperature, and Li/LFP full cell with QSCE-PH/GPFIL30 shows superior rate performance (high specific capacities of 79 mAh-g(-1) at 30 degrees C and 5 C) and excellent cycling performance (high capacity retention of 91% after 500 cycles at 80 C and 1 C).