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Phone: þ82 55 772 1668, Fax: þ82 55 772 1670During discharge of lithium sulfur (Li-S) battery with a liquid electrolyte system, sulfur is first reduced to Li 2 S 8 , which is dissolved into the organic electrolyte and this serves as the liquid cathode. In solution, lithium polysulfides undergo a series of chemical reactions and their concentration varies during cell reaction. The amount of sulfur and electrolytes in the system plays an important role in determining the cell performance. In this work, the effect of sulfur loading in cathode and the amount of electrolyte on the energy density and cycle performance of Li-S battery has been investigated. Cathodes with sulfur loading of 0.99, 2.98, and 6.80 mg_S cm À2 were prepared. Precisely controlled amount of electrolyte was added with varied electrolyte/sulfur (E/S) ratios of 1.67, 5, 10, 20, and 40 ml/mg_S. The surface morphology of fresh and cycled sulfur cathodes was characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).

The surface decoration of CoS2 on SPAN–CNT nanofibers endows lithium–sulfur (Li–S) batteries with outstanding capacity reversibility and high energy density.

Organic cathode materials are of great interest for application in batteries due to their abundant availability and environmental compatibility. An approach to make long chain molecules of these organic materials in order to overcome the problem of dissolution in a liquid electrolyte (LE) and incorporate a highly conducting material to enhance the poor electric conductivity of these materials would be of great research interest. In this work, a novel polyimide (PI)/multiwalled carbon nanotube (MWCNT) nanocomposite is prepared as the cathode material for organic Na-ion batteries (NIBs), via a two-step imidization reaction using perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and diaminopropane (DAP) to form an insoluble PI. The MWCNT in the composite serves as the conductive channel to maximize the utilization of the active material in the electrode. Furthermore, a three-dimensional fiber network is prepared from an electrospun polyacrylonitrile nanofibrous membrane and used as a gel polymer electrolyte (GPE) with efficient electrolyte uptake and high ionic conductivity. The combination of the PI/MWCNT nanocomposite cathode and GPE results in a highly efficient organic NIB with an ultralong life span of 3000 cycles and stable cycle performance at high C-rates.