A Homogeneous Janus Membrane Based on Functionalized MOFs Crosslinked by Aramid Nanofibers for Quasi‐Solid‐State Lithium Sulfur Batteries

Abstract Lithium–sulfur batteries (LSBs) are considered as promising candidates in the next generation of high energy density devices. However, the serious shuttle effect, irreversible dendrite growth of Li metal anode, and the potential safety hazard impede the practical application of LSBs. Herein, a novel homogeneous Janus membrane based on functionalized MOFs crosslinked by aramid nanofibers is designed and synthesized to simultaneously solve the above challenges in quasi‐solid‐state LSBs. The aramid nanofibers with good mechanical properties and thermal stability act as a homogeneous scaffold to crosslink the MOF particles with different ligands on both sides and this Janus membrane upgrades the stability and safety on both the cathode and anode. Specifically, the amino ligand‐decorated MOFs contribute to homogenize Li‐ion flux and stabilize the lithium anode, and the sulfonic ligand‐decorated MOFs effectively suppress the shuttle effect by the dual effects of chemical adsorption and electrostatic repulsion. The quasi‐solid‐state LSBs assembled with this homogeneous Janus membrane deliver excellent rate performance and cycling stability. Moreover, it exhibits a high initial capacity of 923.4 mAh g−1 at 1 C at 70 °C, and 697.3 mAh g−1 is retained after 100 cycles, indicating great potential for its application in high‐safety LSBs.