A defective MOF architecture threaded by interlaced carbon nanotubes for high-cycling lithium-sulfur batteries

Abstract

Metal organic frameworks (MOFs) have been deemed among the most promising sulfur hosts for lithium-sulfur (Li-S) batteries owing to their high specific surface areas, novel pore structures and open metal sites. However, their highly coordinated, electronically insulating and structurally unstable nature overshadows the merits of MOFs to a great extent. In this work, a novel UiO-66/carbon nanotube (UC) composite was initially synthesized via a facile one-pot synthesis strategy, in which abundant linker-missing defects were caused by introduced competitive coordination. Meanwhile, flexible and interlaced carbon nanotubes (CNTs) throughout mechanically stable UiO-66 nanoparticles constructed a reliable conductive network. Because of its superior structural stability, high electronic conductivity and strong polysulfide chemisorption, the UC architecture as the sulfur cathode in Li-S batteries shows stable cycling, delivering an initial capacity of 925 mA h g-1 at 0.5 A g-1 and a very low fading rate over 800 cycles of 0.071% per cycle at 1 A g-1. A strong chemical affinity between coordination defects and LiPSs was revealed by first principles calculations and apparent absorption, which indicates significant entrapment of soluble polysulfides by the UC composite, thus leading to the outstanding cycling performance of S@UC electrodes.