Double-Shelled\nCo₃O₄/C Nanocages\nEnabling Polysulfides Adsorption for High-Performance Lithium–Sulfur\nBatteries

Abstract

Rechargeable\nlithium–sulfur (Li–S) batteries, which\noriginate from the merits of extraordinary theoretical specific energy\ndensity, abundant resources, and eco-friendly character, have received\never-growing attention. However, their practical applications are\nseriously hampered because of the poor conductive property of the\nsulfur and the discharging products, severe dissolution and migration\nof lithium polysulfide intermediates, and huge volumetric variation\nof sulfur particles upon cycling. Here, double-shelled Co₃O₄ and carbon (Co₃O₄/C) hollow nanocages\nas sulfur host materials are reported. The double-shelled structures\ncan significantly boost the adsorption of soluble polysulfides and\nthe electrical conductivity of sulfur cathodes. Consequently, the\nprepared S@Co₃O₄/C cathodes achieve considerable\ncapacity enhancement and excellent rate capability, combining the\ndurable cycling life at 1 C for 500 cycles, in which the overall capacity\nfading remains as low as 0.083% per cycle. Upper-plateau (<i>Q</i>_H) and lower-plateau (<i>Q</i>_L) capacities, static adsorption of polysulfides, and X-ray\nphotoelectron spectroscopy (XPS) analyses unveil the underlying nature\nof the chemical interactions between polysulfide species and the sulfur\nhost. The present results will favor the design and screening of prospective\nhost materials to boost future Li–S batteries.