Ligand engineering of metal-organic frameworks as efficient electrocatalysts for wide-temperature lithium-sulfur batteries

Wide-temperature lithium-sulfur (Li-S) batteries are currently garnering significant attention; however, sluggish redox kinetics at low temperature and serious shuttle effect at high temperature severely hinder their actual application. Herein, a ligand-engineered metal organic framework (MOF) electrocatalyst, NiDMBD (DMBD, 2,5dimercaptoterephthalate), is presented as a fancy separator modifier to tackle these issues. The thiolfunctionalized ligands endow NiDMBD with unique Ni-S coordination links and a nanosheet-assembled flower-like morphology. Joint experimental-theoretical study discloses that the abundant accessible S sites have strong affinity to polysulfides, guaranteeing the inhibition of the polysulfide shuttling. On the other hand, the Ni-S coordination enables fast electron transfer in NiDMBD, thus enhancing the electron conduction and bilaterally catalytic activity toward polysulfide conversion. Consequently, the NiDMBD-engaged Li-S cells exhibit an excellent rate capability (681 mAh g- 1 at 5 C) and admirable cycling steadiness (0.047 % decay rate for 1000 cycles at 2 C) at room temperature. Furthermore, the assembled cells using the NiDMBD separator keep stable cyclic performance across a wide temperature range, from-20 degrees C to 60 degrees C. These promising findings provide insight to the rational design of MOF electrocatalysts for wide-temperature Li-S batteries.