Ion‐Inserted Metal–Organic Frameworks Accelerate the Mass Transfer Kinetics in Lithium–Sulfur Batteries

Abstract Lithium–sulfur battery promises great potential to promote the reform of energy storage field. Modified functional interlayer on separator has been recognized as efficient method to promote battery performances, mainly focusing on the entrapment and catalytic effect toward lithium polysulfide, while the mass transfer property across the interlayers has not been carefully considered. Herein, a dense layer composed of ion‐inserted metal–organic frameworks is used to facilitate mass transfer across the layer and ensure high polysulfides entrapment efficiency. In situ Raman study reveals that the dense functional layer blocks the transfer of Li ions, while the ion‐inserted layer can accelerate the ion‐transfer kinetics and avoid the ion depletion caused polarization. As a result, a specific capacity of 742 mAh g⁻¹ is obtained at 2 C, with the decay rate of 0.089% per cycle at 1 C over 600 cycles, demonstrating great potential for the application in advanced Li–S batteries.