Hierarchical MoS₂@N-Doped Carbon Hollow Spheres with Enhanced Performance in Sodium Dual-Ion Batteries

Sodium dual-ion batteries (S-DIBs) are attracting increasing interest in large-scale electrical energy storage, owing to low-cost and abundant sodium resources and the crucial need to develop high-performance anode materials to spur the large-scale application of S-DIBs. In this work, hierarchical hollow spheres assembled from interconnected few-layer MoS₂ nanosheets with an N-doped carbon coating (designated as MoS₂@NC HHSs) are designed and synthesized. An S-DIBs full cell is fabricated with MoS₂@NC HHSs as the anode, expanded graphite as the cathode, and 1.0 M NaPF₆ in EC/DMC/EMC (1 : 1 : 1, volume ratio) as the electrolyte. The combined effects rendered by the ultrathin MoS₂ subunits, hollow interior, and N-doped carbon coating not only promote the reaction kinetics and capacitive-controlled Na storage, but also guarantee outstanding mechanical stability during Na⁺ intercalation/deintercalation. The MoS₂@NC HHSs-based S-DIBs deliver a high reversible capacity of 45 mAhg⁻¹ at 2 Ag⁻¹ and exhibit good cycling performance with a stable reversible capacity of 40 mAhg⁻¹ and high coulombic efficiency beyond 90 % at 1 Ag⁻¹ for 500 cycles. The MoS₂@NC HHSs have great potential in high-performance S-DIBs.