CNTs/MOFs-derived carbon/Al2(OH)2.76F3.24/S cathodes for high-performance lithium-sulfur batteries

We for the first time rationally design CNTs twinned MOFs-derived porous carbon sponges (CNTs/MOFs-C) through an electrostatic interaction between positively charged MOFs-C and negatively charged CNTs, novel Al2(OH)2.76F3.24 hydroxyhalide nanoparticle with hydroxyl functional groups and polar bonds is in-situ incorporated. The electrochemical performance of lithium-sulfur batteries (LSBs) based on CNTs/MOFs-C/Al2(OH)2.76F3.24/S cathode can be superior to reported LSBs performance, showing a specific capacity of 889 mA h g−1 at 300th cycle at current density of 500 mA g−1. Notably, a longest cycling life span of 2000 cycles at high current density of 2 A g−1 with a specific capacity of 719 mA h g−1 maintained and coulombic efficiency of approximately 100% based on CNTs/MOFs-C/Al2(OH)2.76F3.24/S cathode is reported. Coupling of CNTs with MOFs-C to form 3D interconnected network can provide an efficient pathway for fast ion delivery and electron transport, effectively enhances charge transfer kinetics. The in-situ formation of Al2(OH)2.76F3.24 polar nanoparticles further immobilize sulfur species by strong chemical interactions between the intermediate polysulfides and hydroxyl functional groups, Al-F polar bonds. The rational design route for hydroxyhalide nanoparticle anchored MOFs-derived porous carbon sponges interlinked by CNTs is novel and inspiring, opening up a new gate for sulfur hosts in LSBs.