Rational design of a functional interlayer to simultaneously suppress lithium polysulfides shuttling and facilitate Li-ion migration for high-performance Li-S battery

Lithium-sulfur (Li-S) battery has been considered to be the most promising next-generation secondary battery system, but the shuttle effect of lithium polysulfides (LiPSs) and sluggish redox kinetics of LiPSs conversion processes still hinder its commercial application. Herein, a honeycomb-like structured and dense layer coated interlayer with Co nanoparticles uniformly dispersed was fabricated via a modified phase inversion method followed by carbonization. This interlayer can suppress the LiPSs shuttling by physically blocking the diffusion of LiPSs and chemically capturing and accelerating the conversion of LiPSs due to the high catalytic activity of Co nanoparticles. Meanwhile, the abundant lithiophilic pyridinic N sites can also facilitate Li+ migration, which further promotes the reaction kinetics of LiPSs conversion. Consequently, the Li-S battery assembled with this interlayer can exhibit an excellent specific capacity of 586.6 mAh/g after 400cycles at 4.0C with a low decay rate of 0.10 %. Even when the sulfur loading is elevated to 5.1 mg cm−2, this battery can still maintain the specific capacity of 646.0 mAh/g after 100cycles at 0.2C. This work demonstrates the importance and potential of the rational design of interlayer structure and composition in improving the overall Li-S battery performance.