Micro-MoS2 with excellent reversible sodium-ion storage.

Low storage capacity and poor cycling stability are the main drawbacks of the electrode materials for sodium-ion (Na-ion) batteries, due to the large radius of the Na ion. Here we show that micro-structured molybdenum disulfide (MoS2 ) can exhibit high storage capacity and excellent cycling and rate performances as an anode material for Na-ion batteries by controlling its intercalation depth and optimizing the binder. The former method is to preserve the layered structure of MoS2 , whereas the latter maintains the integrity of the electrode during cycling. A reversible capacity of 90 mAh g(-1) is obtained on a potential plateau feature when less than 0.5 Na per formula unit is intercalated into micro-MoS2 . The fully discharged electrode with sodium alginate (NaAlg) binder delivers a high reversible capacity of 420 mAh g(-1) . Both cells show excellent cycling performance. These findings indicate that metal chalcogenides, for example, MoS2 , can be promising Na-storage materials if their operation potential range and the binder can be appropriately optimized.