Multifunctional Effect of Carbon Matrix with Sulfur Dopant Inspires Mixed Metal Sulfide as Freestanding Anode in Sodium‐Ion Batteries

Abstract As active materials for large‐radius Na⁺ storage, metal sulfide (MS) anodes still face several challenges, including poor intrinsic electric conductivity, severe volume change along with the shuttle and dissolution effects of discharge‐produced polysulfides. In this work, the mixed nickel‐manganese sulfides (NiMnS) in the morphology of uniform 2D ultrathin nanosheets are derived from layered metal‐organic frameworks (MOFs), where the NiS‐MnS heterojunction are accommodated in carbon matrix with S dopant (NiMnS/SC). Through experiments and density functional theory (DFT) simulations, it is revealed that the carbon matrix with S dopant has multifunctional effects on active NiMnS during the charge/discharge process, including conductive intermediary, electrochemical active site, physical barrier, and chemical adsorption. This work may promote the design of MS‐based electrodes in SIBs and extend the application of carbon material with S dopant in Na‐S batteries.