Dual MXene/COF separator with ion-sieving channels and electrocatalytic surfaces for high-performance and durable...

The commercialization of lithium-sulfur (Li-S) batteries is hindered due to issues including severe polysulfide shuttling and dissolution, lithium dendrite growth, and sluggish redox kinetics. Herein, we design a collaborative system based on the emerging two-dimensional material Ti₃C₂ MXene and a covalent organic framework (COF) for separator modification in Li-S batteries. Especially, Ti₃C₂ MXene with high electronic conductivity and abundant surface functional groups can effectively promote the transformation of polysulfides, and the uniform pore structure of the COF can facilitate homogeneous lithium deposition through ion screening, suppressing the growth of lithium dendrites and improving cycle stability. The closely stacked MXene acts as a physical barrier, further inhibiting the penetration of polysulfides through the interlayer gaps of the top-layered COF. The battery delivered remarkable electrochemical performance with a high initial specific capacity of 989.71 mAh g^-1 at 1C and maintained excellent cycling stability at 0.1C under a high S loading of 5.93 mg cm^-2. This work not only describes the roles and advantages of a collaborative system of MXene and a COF in Li-S batteries but also highlights the feasibility of the application of complementary strategies for achieving high-performance Li-S batteries.