The Effect of Compaction Density of Sulfur/Carbon Cathodes on the Practical Application of Li-S Pouch Cells

Lithium-sulfur (Li-S) batteries are a promising electrochemical energy storage device due to their low cost, high energy density, and excellent sustainability, making them superior to many commercial lithium-ion batteries. Despite the great road to market, Li-S batteries still suffer from low practical energy density, which is intimately related to fundamental scientific and technological issues of sulfur cathodes. As a non-negligible parameter in sulfur cathodes, the compaction density plays a crucial role in the energy density of Li-S batteries. Herein, the effect of compaction density of sulfur/carbon cathodes on the electrochemical performance of Li-S batteries is investigated. It is demonstrated that sulfur/carbon cathodes with an optimized compaction density of 1.2 g cm(-3) not only can guarantee the good contact of active materials, but can also ensure the rational dosage of electrolyte, thereby increasing the sulfur utilization as well as reducing the dissolution of polysulfide into the electrolyte. As a result, the pouch cells paired with the sulfur/carbon cathode and Li metal anode deliver superior specific capacity and remarkable cycling performance, which is attributable to the better contact between particles and the faster redox kinetics. This work reveals the contribution of the compaction density of the sulfur cathode to the electrochemical performance of the Li-S battery, providing an instructive paradigm for the rational design of an advanced sulfur cathode for large-scale commercialized Li-S pouch cells.