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

Abstract

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.