Sodium-ion storage mechanisms and design strategies of molybdenum-based materials: A review

The widespread application of renewable clean energy has been regarded as the essential route to cope with the climate crisis, efficient energy storage and conversion is essential for the realization of this inviting vision. Among all these invented electrochemical devices, sodium-ion batteries (SIBs), with abundant resources, relative high safety, similar physical-chemical properties with lithium, have aroused substantial attention in the past decades. Although hard carbon has been demonstrated their intriguing sodium storage capability through intercalation and adsorption, the reversible capacity of hard carbon is lower than that of some metal compounds, metal, and alloying materials, which store sodium ion through conversion reaction and alloying reactions. Considering this, numerous non-carbonaceous anode materials are extensively explored. Among them, molybdenum (Mo) based materials are one of the most substantial investigated anode materials in SIBs because of their intriguing electronic conductivity, conducive crystal structure, and high reversible capacity. To pushing the research of Mo based materials forward, in this review we thoroughly discuss the recent progress of Mo-based materials (including Mo oxides, sulfides, selenides, carbides, phosphides, and nitrides) on synthesis methods, energy storage mechanism, design strategies, and electrochemical performance. Moreover, the future opportunities and crucial challenges of Mo based materials and SIBs facing the battery market are prudently proposed.