Fabrication of MXene/MOF composite separators for high performance lithium-sulfur batteries

Abstract

Lithium-sulfur batteries have attracted much attention due to the high theoretical specific capacity and energy density; however, the shuttle effect of polysulfides hinders the commercialization of lithium-sulfur batteries. In this work, a kind of two-dimensional MXene-MOF (Ti₃C₂T_x-UIO-66-NH₂) composite material was designed as the separator. The Ti₃C₂T_x provides excellent specific surface area and conductivity, while UIO-66-NH₂ owns high porosity and microporous channels. Such synergistic effect endows Ti₃C₂T_x-UIO-66-NH₂ to not only physically suppress the shuttle of polysulfides, but also to promote the catalytic conversion of polysulfides. The battery equipped with Ti₃C₂T_x-UIO-66-NH₂ displays a high initial specific capacity of 1247 mAh g⁻¹ at 0.1C with a decay rate of 0.04093 % per cycle even after 1500 cycles. Furthermore, the mechanism is rationalized from the perspective of theoretical calculations. This strategy paves an avenue to design separator with high performance and advance the practical application of lithium-sulfur batteries.