Hollow urchin-like Mn3O4 microspheres as an advanced sulfur host for enabling Li-S batteries with high gravimetric energy density

Abstract

Lithium-sulfur (Li-S) batteries are considered to be promising candidates for next-generation storage systems. However, the practical applications are still hindered by the severe capacity decay, mainly caused by the large volume change, polysulfide shuttle and sluggish sulfur conversion kinetics. Herein, hollow urchin-like Mn3O4 (HU-Mn3O4) microspheres as sulfur hosts have been synthesized by the hydrothermal method and calcination treatment, aiming to prevent the polysulfide dissolution (benefiting from the strong polysulfide anchoring effect of Mn3O4) and alleviate the volume expansion of sulfur (benefiting from the special hollow structure). Meanwhile, the urchin-like thorny surface also facilitates the rapid ion/electron transfer and the abundant active sites for the fast sulfur redox kinetics. When used as the sulfur host in Li-S batteries, the S@HU-Mn3O4 cathode delivers a high initial capacity of 1137.4 mAh g−1 with a slow capacity decay of 0.042% after 200 cycles at 0.2 C. Even under the conditions of lean electrolyte (E/S = 7 mL g−1) and low N/P ratio (N/P = 2.1), the S@HU-Mn3O4 cathode still enables a stable cycling performance with a high gravimetric energy density (202 Wh kg cell−1), demonstrating its great potential in the development of future practical Li-S battery materials.