Electrochemically Induced High Capacity Displacement Reaction of PEO/MoS2/Graphene Nanocomposites with Lithium
Nanocomposites comprised of poly(ethylene oxide), molybdenum disulfide, and graphene were prepared by the hydrolysis of lithiated molybdenum disulfide in an aqueous solution of PEO and graphene. Structural analysis by XRD shows the nanocomposites are disordered with an expansion of similar to 6 angstrom in the interlayer spacing. During the first discharge, the nanocomposites electrochemically dissociates irreversibly into Li2S and Mo and are able to continously cycle as Li2S +Mo/Li-x <-> S + Mo + Lix+2 as shown by XRD of the discharged electrodes at different depth of discharge (DOD), cyclic voltammetry (CV), and high resolution TEM. A significant increase of the reversible capacity is found in as-prepared MoS2/PEO/graphene composite. The results suggest a new electro-interaction between lithium and molybdenum metal that only occurs in the nanoregime and is enhanced by PEO. The addition of 2 wt% of graphene to the nanocomposites greatly increases the rate capability with rates as high as 10000mA g(-1) yielding > 250mAh g(-1) and recovering to > 600 mAhr g(-1) at 50mA g(-1).