Facile preparation of a lightweight multifunctional interlayer for high-performance Li-S batteries

The construction of functional interlayers for separator modification in Li-S batteries has been proven to be a feasible and effective strategy to alleviate the shuttle effect. However, several challenging issues in interlayer design and fabrication, including the tedious material preparation process and high weight loading of the interlayer on the pristine separator, jeopardize the battery energy density. In this work, a nitrogen-abundant nanoporous carbon/graphene (NC/G) composite was synthesized by a facile method and fabricated into a lightweight membrane, which was investigated as a multifunctional interlayer in a Li-S battery. The abundant nitrogen sites and nanoporous structure of NC/G can effectively anchor and trap polysulfides; graphene (G) can create an excellent conductive network in NC/G. These attributes of NC/G are able to efficiently boost the sulfur redox reaction kinetics and significantly suppress the shuttle effect, leading to superb battery performance. More importantly, the low density of NC/G was conducive to reducing the load on the separator, thus reducing the decline in battery energy density, which is promising for practical applications. Even at an ultra-low loading of NC/G on the pristine separator (0.08 mg cm^-2), the battery showed a competitive electrochemical performance compared with many reported materials. We believe this work provides a strategic guidance for the future fabrication of promising functional interlayers for practical Li-S battery applications.