Constructing FeP/Fe(PO3)3 heterojunction with built-in electric field effect to balance the adsorption and conversion of polysulfides in LiS battery

The development of Lithium‑sulfur batteries (LSBs) is considerably limited by the shuttle effect and slow redox kinetics, which result in low cycle stability and decreased energy density. To enhance the energy density and accelerate the reaction kinetics of LSBs, a heterostructure consisting of FeP/Fe(PO 3 ) 3 nanoparticles was anchored on three-dimensional hierarchical porous carbon nanosheets using a simple soaking and carbonization method. This FeP/Fe(PO 3 ) 3 heterojunction, featuring an intrinsic built-in electric field (BIEF) effect and sulphiphilic characteristics, exhibited high catalytic efficiency in trapping lithium-polysulfides (LiPSs), regulated the nucleation of Li 2 S, and accelerated oxidation conversion reactions. The 3D porous hierarchical carbon nanosheets, derived from corn stalks, provide a large surface area and numerous pores, which effectively accommodate the considerable volume expansion of S 8 and Li 2 S during the electrochemical reactions, while also offering a conductive network to facilitate electron and Li + ion transport. As expected, the PCS/FeP/Fe(PO 3 ) 3 @S cathode demonstrated excellent electrochemical performance, delivering a discharge capacity of 663.8 mAh g −1 at a current rate of 5.0C. Additionally, the constructed Li S pouch cell achieved a high areal capacity of 11.0 mAh cm −2 and maintained an energy density of 450 Wh kg −1 with a sulfur mass loading of 9.0 mg cm −2 . This work provides a novel approach to developing stable, high-energy-density LSBs for practical energy storage applications.