Geometric design of carbon-based interlayer for advanced lithium-sulfur batteries

Interlayer engineering is considered as an innovative and efficient approach to constrain the shuttle effect of polysulfides while elevating sluggish redox reaction kinetics in lithium-sulfur (Li-S) batteries. However, the principles for functional interlayer design have not been scientifically established yet, as very few works have focused on the investigation of parameters (e.g., geometrical structure) that affect the electrochemical performance of interlayer. In this study, interlayers with identical chemical compositions but different micromorphologies are fabricated by polyacrylonitrile, including nanofiber, short stick, and powder. Multiphysics simulation and experimental results reveal that the distinctions in the microcrystalline interlayers lead to completely different suppression effects on polysulfides. Notably, the 3D carbon nanofiber-modified interlayer (NF) prepared from electrospinning technology forms a higher specific area and continuous electron access compared to short sticks and powder. Accordingly, the NF-based Li-S battery exhibited excellent cycling performance at 1.0 C, with a reversible capacity of 660 mAh g-1 after 300 cycles and a decay rate of about 0.10 %. Even at a high sulfur loading of 8.2 mg cm-2, it achieves a high areal capacity of 5.1 mAh cm-2 after 100 cycles at 0.2 C. This study clearly elucidates a design strategy for high-performance interlayer in Li-S batteries from a mesoscale perspective.