Synergizing Spatial Confinement and Dual-Metal Catalysis to Boost Sulfur Kinetics in Lithium–Sulfur Batteries

Abstract

Sluggish kinetics and parasitic shuttling reactions severely impede lithium–sulfur (Li–S) battery operation; resolving these issues can enhance the capacity retention and cyclability of Li–S cells. Therefore, an effective strategy featuring core–shell-structured Co/Ni bimetal-doped metal–organic framework (MOF)/sulfur nanoparticles is reported herein for addressing these problems; this approach offers unprecedented spatial confinement and abundant catalytic sites by encapsulating sulfur within an ordered architecture. The protective shells exhibit long-term stability, ion screening, high lithium-polysulfide adsorption capability, and decent multistep catalytic conversion. Additionally, the delocalized electrons of the MOF endow the cathodes with superior electron/lithium-ion transfer ability. Via multiple physicochemical and theoretical analysis, the resulting synergistic interactions are proved to significantly promote interfacial charge-transfer kinetics, facilitate sulfur conversion dynamics, and inhibit shuttling. The assembled Li–S batteries deliver a stable, highly reversible capacity with marginal decay (0.075% per cycle) for 400 cycles at 0.2 C, a pouch-cell areal capacity of 3.8 mAh cm−2 for 200 cycles under a high sulfur loading, as well as remarkably improved pouch-cell performance.