Amorphizing metal-organic framework towards multifunctional polysulfide barrier for high-performance lithium-sulfur batteries

Rational design of separator is especially critical in lithium-sulfur (Li–S) battery electrochemistry in view of the highly mobile intermediates and their detrimental chemical/electrochemical side reactions, which give rise to the notorious “shuttle effect”. Herein, we develop a novel strategy of amorphizing metal organic framework (MOF) exemplified by MIL-88B to construct advanced separator for Li–S batteries. The amorphization is achieved via a simple ligand competition method, and the product is endowed with higher adsorbability and catalytic activity to sulfur species attributed to the undercoordination effect. Therefore, Li–S batteries with the as-developed amorphous MOF (aMIL-88B)-modified separator realize efficient and reversible sulfur electrochemistry, exhibiting superb cyclability with high capacity retention of 740 mAh g−1 after 500 cycles at 1 C, rate performance up to 5 C, and also decent areal capacity under a high sulfur loading of 4.3 mg cm−2. This work provides a facile pathway towards multifunctional separators in Li–S batteries, and is also instructive to defect engineering of advanced materials in other related energy storage fields.