Sustainable metal-organic framework co-engineered glass fiber separators for safer and longer cycle life of Li-S batteries

Most of the issues with making Li–S batteries are caused by the growth of Li dendrites and the movement of polysulfide. To solve both of these problems at the same time, this study describes the placement of Cu or Fe atoms on an ultrathin metal organic framework (MOF) nanosheet-based glass fiber separator for making Li–S batteries that are safe and last a long time. Cu or Fe atoms coordinated with oxygen atoms on the surface of ultrathin MOF nanosheets can greatly facilitate the movement of Li ions while acting as “traps” to stop polysulfide from moving around by introducing the Lewis acid-base interaction. Because of this, the Li–S cells with the Cu/MOF or Fe/MOF coatings on the glass fiber separator show long-term cycling stabilities with low-capacity decay of 0.080% and 0.057% per cycle over 400 cycles, respectively. Furthermore, Li–S cells assembled with the Cu/MOF and Fe/MOF separators show capacity retention of 985 and 1237 mAh g⁻¹, respectively, after 400 cycles, indicating the potential of the Cu/MOF and Fe/MOF separators for practical applications.