Yolk-Shelled C@Fe3 O4 Nanoboxes as Efficient Sulfur Hosts for High-Performance Lithium-Sulfur Batteries.

Abstract

Owing to the high theoretical specific capacity (1675 mA h g-1 ) and low cost, lithium-sulfur (Li-S) batteries offer advantages for next-generation energy storage. However, the polysulfide dissolution and low electronic conductivity of sulfur cathodes limit the practical application of Li-S batteries. To address such issues, well-designed yolk-shelled carbon@Fe3 O4 (YSC@Fe3 O4 ) nanoboxes as highly efficient sulfur hosts for Li-S batteries are reported here. With both physical entrapment by carbon shells and strong chemical interaction with Fe3 O4 cores, this unique architecture immobilizes the active material and inhibits diffusion of the polysulfide intermediates. Moreover, due to their high conductivity, the carbon shells and the polar Fe3 O4 cores facilitate fast electron/ion transport and promote continuous reactivation of the active material during the charge/discharge process, resulting in improved electrochemical utilization and reversibility. With these merits, the S/YSC@Fe3 O4 cathodes support high sulfur content (80 wt%) and loading (5.5 mg cm-2 ) and deliver high specific capacity, excellent rate capacity, and long cycling stability. This work provides a new perspective to design a carbon/metal-oxide-based yolk-shelled framework as a high sulfur-loading host for advanced Li-S batteries with superior electrochemical properties.