Tailoring the Function of Battery Separators via the Design of MOF Coatings

Separators serve as critical components in batteries, bearing the responsibility for battery safety. In addition to the demand for increased flame resistance of separators, there is a growing interest in the additional functions of battery separators. In this work, a multifunctional coating integration strategy is proposed for battery separators via the versatility of metal–organic frameworks. A versatile and high-safety MIP-202@2320 composite separator is engineered and it is integrated into lithium–sulfur batteries. The presence of Cl − and the porous structure of MIP-202 impart flame-retardant characteristics and high electrolyte retention (80%) to resulting separators. Moreover, coupled with the negatively charged electron cloud formed by Cl − ions within the channels, it can selectively impede the polysulfides from migrating toward the anode, while concurrently facilitating the movement of Li + ions. The assembled lithium–sulfur battery with MIP-202@2320 as the separator maintains an impressive 71.8% capacity retention even after 600 cycles at a 0.5C rate. This multifunctional integration strategy not only boosts the performance of lithium–sulfur batteries but also pioneers a new direction for the design of future battery separators for different kinds of batteries.