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.