Separator modified by Co-porphyrin based Zr-MOF@CNT composite enabling efficient polysulfides catalytic conversion for advanced lithium-sulfur batteries

Abstract

The shuttle effect of soluble polysulfides as one of the primary bottlenecks has retard the widespread use of lithium-sulfur (Li-S) batteries. In this work, a new functional separator coating composed of pristine zirconium metal-organic framework (Co-PCN-222) with catalytic cobalt-porphyrin linker decorated carbon nanotubes (PCN@CNT) was presented for addressing this problem. Benefiting from powerful adsorption and catalytic activity of the uniformly dispersed cobalt and nitrogen sites in porphyrin linkers as well as the fast electron transport network provided by highly conductive CNT, the polysulfide redox kinetics is greatly boosted and the shuttle effect is inhibited to a large extent. Accordingly, the Li-S batteries coupling with PCN@CNT coated separator delivers a specific capacity as high as 1157 mAh g−1 at 0.1 C, good rate capability with a reversible capacity of 696 mAh g−1 under 2 C as well as excellent cyclic performance with a low average capacity attenuation rate of 0.067% upon 500 cycles at 1 C. This work will open up great opportunities in the development of pristine MOFs-based separator coating for advanced Li-S batteries.