PPy-constructed core–shell structures from MOFs for confining lithium polysulfides. Issue 10 (13th April 2022) - Geng, Pengbiao
Abstract : Core–shell structured MIL-96-Al composites are prepared through a melt-diffusion method followed by a water-phase polymerization process. The composites can strongly confine lithium polysulfides in a cathode. Abstract : For sulfur host materials in Li–S batteries, the structure is important for suppressing the shuttle effect and buffering the volume expansion. A polypyrrole (PPy)-coated core–shell structure is obtained with porous MIL-96-Al as the skeleton by a melt-diffusion method and a water-phase polymerization process, named as MIL-96-S-PPy. The strong chemical interaction between the lithium polysulfides (LPS) and the PPy shell can prevent the diffusion of LPS from the cathode to the anode. The electron-rich PPy shell can bond with electropositive Li + in LPS by a polar–polar interaction and buffer the volume expansion. Moreover, the porous MIL-96-Al can provide free space for sulfur impregnation, resulting in improved coulombic efficiency and sulfur utilization. With the help of the PPy-coated core–shell structure, the initial specific capacity could achieve 1233.8 mA h g −1 at 0.5 C. This work provides a new perspective to design a core–shell structure as a high-performance sulfur cathode for advanced Li–S batteries.