Sulfur Cathodes with Carbon Current Collector for Li-S cells

Li-S cells have a low voltage (similar to 2.1 V), but their potentially high energy density (200-500 Wh/kg) makes them a promising system for next generation batteries. To obtain high energy densities on cell level, the weight fraction and load of the active material should be as high as possible, while inactive material is reduced to a minimum. Conventionally, sulfur slurry cathodes with an aluminum current collector are used. However, binder-free CNT-coated carbon structures are a promising method of achieving higher loads and higher ratios of active material. Using a specially designed test cell it was demonstrated that sulfur cathodes without a metal current collector can deliver enough power to meet the requirements of consumer electronics at simultaneously high capacities of up to 600 mAh g(-1) for the entire electrode and current collector. A literature study compared various equivalent circuits used for Li-S electrochemical impedance spectroscopy (EIS), and enabled the selection of the most suitable one for the system used here. EIS measurements during charge and discharge delivered vital information about the specific resistances of the sulfur cathodes with a carbon current collector. (C) 2013 The Electrochemical Society. All rights reserved.