Effect of sulfur loading on energy density of lithium sulfur batteries

During discharge of lithium sulfur (Li-S) battery with a liquid electrolyte system, sulfur is first reduced to Li2S8, 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(-2) were prepared. Precisely controlled amount of electrolyte was added with varied electrolyte/sulfur (E/S) ratios of 1.67, 5, 10, 20, and 40 mu l/mg_S. The surface morphology of fresh and cycled sulfur cathodes was characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim