Synthesis and Characterization of S-C composite cathodes for Mg-S batteries

Kurzfassung

Efficient and sustainable batteries are a key challenge to pave the way for the availability of energy from renewable sources. Despite the fact that Li-based systems provide a good energy density, they still suffer from some disadvantages concerning cost and safety issues. To overcome these drawbacks alternative systems are under intensive research. Currently sulfur is one of the most promising cathode materials due to its high energy density of 1672 mAh g−1, its low cost and environmental friendliness. Magnesium features significant advantages as it is abundant and shows no dendrite formation during cycling, which ensures superior safety. Above all magnesium offers a high theoretical volumetric and gravimetric capacity of 3832 mAh cm−3 and 2230 mAh g−1 respectively. Thus the combination of a negative magnesium electrode and a positive sulfur electrode (Mg-S) represents a promising cell technology. Until now Mg-S cells suffer from fast capacity decay in the first few cycles and poor cycle stability. To understand the underlying processes and to identify the origin of the rapid degradation, different approaches regarding the synthesis and characterization of S-C electrodes in Mg2+-based electrolyte systems are investigated. The cathodes prepared are characterized with cell cycling experiments and optimized regarding their electrochemical performance. In Addition electrochemical impedance spectroscopy was applied to examine internal processes.