Promotion of reversible Li + storage in transition metal dichalcogenides by Ag nanoclusters

After years of development, improvement in the electrochemical properties of MoS 2 through structural modifications has reached its limit. Further improvements in the Li + storage properties of MoS 2 must be based on an understanding of the Li + storage mechanism in MoS 2 . On this basis, we have developed a novel ternary composite of graphene, MoS 2 nanosheets and a small amount (1 wt%) of silver nanoclusters (NCs; MoS 2 /G/Ag). The presence of the Ag NCs in the composite is, however, instrumental and serves several purposes: immobilization of sulfur, increased association with Li + and increased spacing between graphene sheets. The presence of this small amount of Ag NCs was able to increase the Li + storage capacity of MoS 2 by 60% (with a discharge capacity of ~1300 mAh g −1 at 0.5 A g −1 compared with 800–850 mAh g −1 for a MoS 2 /graphene composite without the Ag NCs (MoS 2 /G)). The MoS 2 /G/Ag composite also exhibited a very impressive rate performance: discharge capacities of 1040 and 850 mAh g −1 at the very high current densities of 1 and 5 A g −1 , respectively (the corresponding values from MoS 2 /G without the Ag NCs are 790 and 580 mAh g −1 ).