Bidirectional redox catalyst with rambutan-like structure for advanced lithium-sulfur battery

The lithium polysulfide (LiPSs) shuttle effect and sluggish conversion kinetics hinder the commercial viability of lithium-sulfur (Li-S) batteries. To improve the properties of Li-S batteries, it is imperative to establish efficient pathways for Li-ions transmission by constructing conductivity channels of high quality, and to expedite the conversion kinetics of LiPSs by employing catalysts of exceptional activity. In this study, we synthesized a spherical superstructure of metal–organic framework nanorods (SS-MOFNR) using a self-assembly strategy with zinc-metal–organic framework (Zn-MOF) nanoparticles, followed by carbonization to obtain the spherical superstructure of carbon nanorods (SS-CNR). Subsequently, palladium nanoparticles were synthesized through the reduction and uniformly dispersed onto SS-CNR. The hollow porous structure facilitates the efficient utilization of sulfur and ensures the rapid diffusion of Li-ions. Additionally, Pd nanoparticles exhibit significant catalytic activity, effectively adsorbing LiPSs and bidirectional catalytic conversion of sulfur species, thereby effectively suppressing the shuttle effect of LiPSs. Therefore S/Pd@SS-CNR electrode demonstrates commendable electrochemical efficacy, as evidenced by its initial specific capacity of 1627.7 mAh g−1 at 0.1C and maintaining a specific capacity of 766.2 mAh g−1 even after 600 cycles at 0.5C. Moreover, it exhibits favorable cycle stability at 2C, retaining a reversible capacity of 502.3 mAh g−1 after undergoing 1000 cycles.