Quasi solid-state composite electrolyte (QSCE-PH/GPFIL3/P) with multifunctional 2D molecular brush fillers is developed to achieve high-performance lithium metal batteries. Our QSCE-PH/GPFIL3/P integrates features of PFIL side-chain-enhanced Li+ conduction, GO-strengthened mechanical property, and LiF-containing SEI layer-facilitated uniform lithium deposition.
Comprehensive Summary
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 () 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-PH/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 μm) self-supporting QSCE-PH/GPFIL3/P exhibits high ionic conductivity (3.24 × 10−4 S·cm−1) and excellent (0.82) at room temperature, and Li/LFP full cell with QSCE-PH/GPFIL3/P shows superior rate performance (high specific capacities of 79 mAh·g−1 at 30 °C and 5 C) and excellent cycling performance (high capacity retention of 91% after 500 cycles at 80 °C and 1 C).