2D Zr-Fc metal-organic frameworks with highly efficient anchoring and catalytic conversion ability towards polysulfides for advanced Li-S battery

Abstract

The practical viability of Li-S battery is largely hampered by undesirable shuttling behavior and sluggish conversion kinetics of polysulfides. Considering that, a multifunctional interlayer, prepared by weaving ferrocene-based two-dimensional (2D) metal-organic framework (Zr-Fc MOF) nanosheets and carbon nanotubes (CNT) via simple vacuum filtration, is proposed to achieve high-performance Li-S battery. Using a combination of in situ Raman spectroscopy, first-principles calculations and systematic electrochemical evaluation, we unveil that the Zr-Fc MOF, as a new polysulfides confinement agent, can not only restrain polysulfides shuttling via both electrostatic attraction and chemical anchoring capability, but also provide excellent electrocatalytic effect on polysulfides redox kinetics. The intertwined CNT throughout Zr-Fc MOF nanosheets facilitates electron conductivity as well as sufficient exposure of capturing and catalyzing active sites of Zr-Fc MOF. Accordingly, attributed to the synergistic entrapping-catalysis-conversion effect, we demonstrate that Li-S cell coupling with the as-prepared Zr-Fc MOF/CNT interlayer exhibits a dramatically enhanced rate performance and outstanding cyclability (1500 cycles at 1 C with ultralow capacity decay rate of 0.027% under sulfur loading of 4.11 mg cm−2). This work will inspire more intelligent 2D MOF materials simultaneously with highly efficient trapping and catalytic conversion of polysulfides for high-energy and long-life Li-S battery.