Mesoporous Carbon Inter layers with Tailored Pore Volume as Polysulfide Reservoir for High-Energy Lithium-Sulfur Batteries

The lithium-sulfur (Li-S) battery is one of the most promising candidates for the next generation of rechargeable batteries owing to its high theoretical energy density, which is 4- to 5-fold greater than those of state-of-the-art Li-ion batteries. However, its commercial applications have been hampered due to the insulating nature of sulfur and the poor cycling stability caused by the polysulfide shuttle phenomenon. In this work, we show that Li-S batteries with a mesoporous carbon interlayer placed between the separator and the sulfur cathode not only reduces the internal resistance of the cells but also that its intrinsic mesoporosity provides a physical place for trapping soluble polysulfides as well as to alleviate the negative impact of the large volume change of sulfur. This improvement of the active material reutilization allows one to obtain a stable capacity of 1015 mAh g-1 at 0.2 C after 200 cycles despite the use of a conventional sulfur-carbon black mixture as cathode. Furthermore, we observe an excellent capacity retention (similar to 0.1% loss per cycle, after the second cycle), thus making one step closer toward feasible Li-S battery technology for applications in electric vehicles and grid-scale stationary energy storage systems.