Impact of composite preparation method on the electrochemical performance of lithium-sulfur batteries

Due to their lower prices, higher energy density, and more environmentally friendly active components, Lithium-Sulfur batteries will soon compete with the current Lithium-ion batteries. However, issues persist that hinder this implementation, such as the poor conductivity of S and sluggish kinetics due to the polysulfide shuttle, among others. The most common strategy to solve these problems is the use of carbon@sulfur (C@S) composites as the cathode of the battery. Composite preparation is a key step for the performance of the electrochemical cell, and yet few studies are focused on this stage. Herein, C@S composites have been prepared following the four most common synthesis methods (melt diffusion; ball milling; dissolution-crystallization; chemical deposition), and in-depth physical-chemical characterization studies and electrochemical analysis have been carried out with these composites in Li-S cells. Properties such as sulfur size, the structural arrangement of the carbon and the type of S infiltration in the matrix have been found to be key parameters in the performance of the composite as a positive electrode in the battery. The comparative analysis shows that the melt diffusion method gives the composite the ideal properties for superior electrochemical performance in tests under different current densities.