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A novel sulfur/polyacrylonitrile/graphene nanocomposite has been synthesized via a simple combination of ballmilling with low temperature heat-treatment. The nanocomposite was examined as a cathode for high performance lithium/sulfur batteries. The SEM and TEM observations revealed that sulfur/polyacrylonitrile particles are incorporated into graphene networks homogenously. Charge/discharge tests and ac impedance spectroscopy have shown improved conductivity and electrochemical properties of the composite with the addition of graphene. The lithium cell with this ternary composite cathode delivered a discharge capacity of 612 mAh g-1 in the second cycle at 0.1 C, and retained about 77% of this value over 100 cycles. Even up to 4 C rate, the lithium cell demonstrated an excellent rate capability, delivering a highly reversible discharge capacity of 360 mAh g-1. [ABSTRACT FROM AUTHOR]

One of the major drawbacks of lithium/sulfur (Li/S) batteries is the dissolution of polysulfides into liquid electrolytes. In order to overcome this difficulty, polymer/silicate nanocomposite electrolytes composed of polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) and different types of nano-layered silicates were fabricated and analyzed. All the electrolyte membranes showed ionic conductivity of 5-7 mS/cm at room temperature and electrochemical stability window up to 4.8 V. Tested by two different sulfur composite cathodes, PVdF-HFP/organically-modified-silicate (OMMT) nanocomposite electrolyte delivered a higher discharge capacity and showed an improved cyclability compared to the other cells. Such electrochemical performance is attributed to the small and uniformly distributed pores within the structure of the polymer nanocomposite membrane, which promotes immobilizing the electrolyte solution and prevents dissolution of polysulfides. [ABSTRACT FROM AUTHOR]