Highly Efficient Polysulfide Trapping and Ion Transferring within a Hierarchical Porous Membrane Interlayer for High-Energy Lithium–Sulfur Batteries

Inserting an interlayer between the sulfur cathode and the separator has been considered as one of the most promising solutions to suppress the shuttle effect of soluble lithium polysulfide intermediates (LiPSs) in lithium–sulfur (Li–S) batteries. However, previously reported carbon nanotubes (CNTs) or carbon composite-based interlayers can be easily blocked by LiPS adsorption and impede the transmission of lithium ions due to the lack of rationally designed porous structures. Here, we prepared a hierarchical porous Fe3C–C/CNT membrane interlayer with rapid ion-transport macropores and hierarchical polysulfide-trapping mesopores via a convenient and scalable phase inversion approach for high-energy-density Li–S batteries. The rationally designed porous structure of Fe3C–C/CNT interlayers significantly provides a good environment for the fast transportation of Li+ ions and electrons, and it simultaneously effectively restrains the shuttle effect by the chemical adsorption energy of the Fe3C nanoparticles toward soluble LiPSs. As a result, due to the self-supporting Fe3C–C/CNT interlayer, batteries with high sulfur loading (7.06 mg cm–2) and a low ratio of electrolyte to sulfur (5.7 μL mg–1) can exhibit a high areal capacity up to 4.32 mA h cm–2, achieving high gravimetric specific energy (1560 W h kg–1) and volumetric specific energy (1694 W h L–1). This facile approach of membrane interlayer fabrication and structural design provides a promising future for practical applications of Li–S batteries.