Theory-guided optimization of central metal for efficient MOFs bidirectional catalysis in lithium-sulfur batteries.

The migration and shuttling of polysulfides between electrodes during the charge-discharge process pose a considerable challenge in the practical application of lithium-sulfur (Li-S) batteries. To address this, the development of functional separators represents an accessible and cost-effective approach to mitigate the shuttling effect and enhance the chemical kinetics of Li-S systems. In this study, a series of MOFs were constructed by tuning the central metal and used as separation modification to explore the effect of the metal ions in the MOFs on the catalytic conversion of polysulfides. Among them, Co-BTTC exhibited fast ion transport and efficiently captured polysulfides, which accelerated the redox kinetics in Li-S batteries. Consequently, the Co-BTTC-modified separator in coin battery achieves a high reversible capacity of 786 mAh g at 1C more than 800 cycles and a minimum capacity degradation of 0.033 % per cycle. In addition, the battery also achieves a capacity of 500 mAh g at 5C after 200 cycles, exhibiting commendable cycle stability. These findings highlight the potential of Co-BTTC as a separator modifier to advance the performance and cyclability of Li-S batteries.