Nonpoisoned metal catalysts enabled by concave carbon confinement for durable sulfur conversion in batteries

Abstract

Metal-sulfur batteries promise sustainable high-energy storage but are plagued by sulfur-induced catalyst deactivation, which hinders long-term sulfur conversion. Here we present a concave carbon surface confinement strategy as a universal design principle to stabilize metal catalysts against sulfur poisoning. By embedding cobalt nanoparticles within curved carbon cavities, the intimate metal-carbon contact area is dramatically enlarged, triggering strong and reversible electron transfer from cobalt (Co) to the carbon scaffold. This unique interfacial architecture creates a balanced Co2+/Co0 valence state (Co2+/Co0 ratio approaching unity) and maintains it during cycling, effectively outcompeting electron donation to sulfur species and suppressing the formation of strong Co–S bonds. Benefiting from this architecture, the Co catalyst exhibits a persistently low activation energy (0.195 eV) for the rate-determining polysulfide-to-Li2S conversion and avoids the gradual activity loss typically observed with conventional carbon-supported catalysts. Consequently, lithium-sulfur batteries deliver an ultralow capacity decay of 0.044 % per cycle over 1000 cycles, while Ah-level pouch cells achieve gravimetric energy densities up to 505 Wh kg-1 and sustain 457 Wh kg-1 with only 0.32 % per-cycle fading. This carbon confinement not only overcomes sulfur poisoning but also provides a general blueprint for designing durable, high-activity metal catalysts in sulfur-rich electrochemical environments.