Double-shelled Co₃O₄/C nanocages enabling polysulfides adsorption for high-performance lithium-sulfur batteries

Rechargeable lithium-sulfur (Li-S) batteries, which originate from the merits of extraordinary theoretical specific energy density, abundant resources, and eco-friendly character, have received ever-growing attention. However, their practical applications are seriously hampered because of the poor conductive property of the sulfur and the discharging products, severe dissolution and migration of lithium polysulfide intermediates, and huge volumetric variation of sulfur particles upon cycling. Here, double-shelled Co₃O₄ and carbon (Co₃O₄/C) hollow nanocages as sulfur host materials are reported. The double-shelled structures can significantly boost the adsorption of soluble polysulfides and the electrical conductivity of sulfur cathodes. Consequently, the prepared S@Co₃O₄/C cathodes achieve considerable capacity enhancement and excellent rate capability, combining the durable cycling life at 1 C for 500 cycles, in which the overall capacity fading remains as low as 0.083% per cycle. Upper-plateau (Q_H) and lower-plateau (Q_L) capacities, static adsorption of polysulfides, and X-ray photoelectron spectroscopy (XPS) analyses unveil the underlying nature of the chemical interactions between polysulfide species and the sulfur host. The present results will favor the design and screening of prospective host materials to boost future Li-S batteries.