A hierarchical nano-MoS₂ flake/micro-MXene lamellar complex structure within a carbon coating for rapid sodium-ion storage

A single two-dimensional material often struggles to satisfy all the performance requirements of electrode materials for sodium-ion batteries. However, constructing a hierarchical heterogeneous two-dimensional stacking structure can effectively combine the advantages of multiple materials and make up for the insufficiency of a single element. This work applied a pre-intercalation-sulphuration concept and liquid-phase coating modification by constructing a hierarchical nano-flake/micro-lamellar complex structure. In this composite material, MoS2 nanosheets and V2C MXene layers overlap and interact to prevent nanoparticle agglomeration and micron flakes collapse simultaneously. The MoS2/MXene hierarchical structure is sandwiched between ultrathin and dense carbon layers to form a multifaceted conductive skeleton and a twofold protection mechanism. The coating reduces the electrolyte contact area and prevents the escape of polysulfide byproducts. Accordingly, the designed MSVC@C demonstrates superior Na+ storage capacities (612.4 mA h g(-1) at 0.5 A g(-1) after 600 cycles) and outstanding rate performance (304.42 mA h g(-1) at 10 A g(-1)). Experimental results and theoretical calculations verify that the MoS2 and V2C heterostructure promotes the electrochemical performance owing to the better electronic conductivity and lower ion diffusion energy barrier. Moreover, this structure optimization strategy applies to various MXene guests (e.g., V2C and Nb2C) to prepare a variety of hierarchical nano-micro structures that are expected to be promising two-dimensional electrode materials for SIBs with application prospects in the future.