Bifunctional design of cerium-based metal-organic framework-808 membrane modified separator for polysulfide shuttling and dendrite growth inhibition in lithium-sulfur batteries

Lithium-sulfur battery is perceived as one promising next generation rechargeable battery system, in view of its high theoretical specific capacity and energy density . However, the “shuttle effect” of polysulfides and the uncontrolled growth of lithium dendrites significantly obstruct its practical application. Herein, a bifunctional separator with double-sided modification is developed to simultaneously resolve these issues, which is constructed by growing continuous cerium-based metal-organic framework-808 (Ce-MOF-808) membranes on both sides of the commercial polypropylene (PP) separator through a simple in-situ growth method. On the cathode side , the Ce-MOF-808 membrane can play multiple roles of adsorption, selective sieving and catalytic conversion towards polysulfides, thereby effectively inhibiting their shuttle effect. On the anode side , the highly uniform pore distribution and polar groups of this MOF membrane ensure the fast and homogenous diffusion of lithium ions , endowing a stable lithium nucleation and growth in the cycles. Consequently, the Ce-MOF-808/PP separator exhibits a high initial specific capacity of 954.7 mAh g −1 under 1 C with a very limited capacity fading of 0.025% in 500 cycles, and an outstanding rate capability. Moreover, the separator also ensures the stable cycling of the battery at raised sulfur loading and lean-electrolyte conditions.