In Situ Conversion of Metal–Organic Frameworks into VO₂–V₃S₄ Heterocatalyst Embedded Layered Porous Carbon as an “All-in-One” Host for Lithium–Sulfur Batteries

Although lithium–sulfur batteries exhibit a fivefold higher energy density than commercial lithium-ion batteries, their volume expansion and insulating nature, and intrinsic polysulfide shuttle have hindered their practical application. An alternative sulfur host is necessary to realize porous, conductive, and polar functions; however, there is a tradeoff among these three critical factors in material design. Here, the authors report a layered porous carbon (LPC) with VO₂/V₃S₄ heterostructures using one-step carbonization–sulfidation of metal–organic framework templates as a sulfur host that meets all the criteria. In situ conversion of V–O ions into V₃S₄ nuclei in the confined 2D space generated by dynamic formation of the LPC matrix creates {200}-facet-exposed V₃S₄ nanosheets decorated with tiny VO₂ nanoparticles. The VO₂/V₃S₄ @ LPC composite facilitates high sulfur loading (70 wt%), superior energy density (1022 mA h g⁻¹ at 0.2 C, 100 cycles), and long-term cyclability (665 mA h g⁻¹ at 1 C, 1000 cycles). The enhanced Li–S chemistry is attributed to the synergistic heterocatalytic behavior of polar VO₂ and conductive V₃S₄ in the soft porous LPC scaffold, which accelerates polysulfide adsorption, conversion, and charge-transfer ability simultaneously.