Fabrication of MoS2-Graphene Nanocomposites by Layer-by-Layer Manipulation for High-Performance Lithium Ion Battery Anodes

This paper reports facile and cost effective methods for fabricating MoS2 nanosheets and for assembling layered MoS2-graphene nanocomposites. The MoS2 nanosheets were obtained by ultrasonicating commercial MoS2 powder in N-methyl-pyrrolidinone (NMP). The MoS2-graphene nanocomposites were assembled by the vacuum assisted filtration of a mixture of the MoS2 nanosheets and graphene nanosheets suspended in NMP and water, respectively. In the nanocomposites, the MoS2 nanosheets are dispersed between the graphene nanosheets, and vice versa. When used as anodes for LIBs, the MoS2 nanosheets greatly outperform the MoS2 powder; however, they still suffer severe capacity deterioration due to the poor electric conductivity and the obvious structural failure. Excellent performances were observed in the MoS2-graphene nanocomposites. For the 60Mo-80GN sample, the reversible capacities are held stably at similar to 650, similar to 550 and similar to 500 mAh g(-1) at 500, 1000 and 20000 mA g(-1), respectively. It is concluded that for the MoS2-graphene nanocomposites, MoS2 is the key component accommodating Li ions, and graphene improves the electric conductivity and maintains the structural stability for the MoS2 nanosheets. These findings prove that ultrasonication combined with the vacuum assisted filtration is a scale-up approach to fabricate MoS2-graphene based layered nanocomposites with excellent Li storage capacity. (C) 2013 The Electrochemical Society. All rights reserved.