Multifunctional Interlayer Engineering for Silkworm Excrement-Derived Porous Carbon Enabling High-Energy Lithium Sulfur Batteries.

Lithium-sulfur (Li-S) batteries show advantage of high theoretical capacity. However, the shuttle effect of polysulfides and sluggish sulfur redox kinetics seriously reduce their service life. Inspired by the porous structural features of biomass materials, herein, a functional interlayer is fabricated by silkworm excrement-derived three-dimensional porous carbon accommodating nano sized CoS particles (SC@CoS ). The porous carbon delivers a high specific surface area, which provides adequate adsorption sites, being responsible for suppressing the shuttle effect of polysulfides. Meanwhile, the porous carbon is favorable for hindering the aggregation of CoS and maintaining its high activity during extended cycles, which effectively accelerates the polysulfides conversion kinetics. Moreover, the SC@CoS functional interlayer effectively limits the formation of Li dendrites and promotes the uniform deposition of Li on the Li electrode surface. As a result, the CMK-3/S cathode achieves a high initial capacity of 1599.1 mAh g at 0.2 C rate assisted by the polypropylene separator coated with the functional interlayer and 1208.3 mAh g is maintained after the long cycling test. This work provides an insight into the designing of long-lasting catalysts for stable functional interlayer, which encourages the application of biomass-derived porous carbon in high-energy Li-S batteries.