Hierarchically Porous Carbon Microspheres Coated with MnO₂ Nanosheets as the Sulfur Host for High-Loading Lithium–Sulfur Batteries

Abstract

Lithium–sulfur (Li–S) batteries have emerged as a promising candidate for next-generation high-energy rechargeable lithium batteries, but their practical application is impeded by the sluggish redox kinetics and low sulfur loading. Here, we report the in situ growth of δ-MnO2 nanosheets onto hierarchical porous carbon microspheres (HPCs) to form an HPCs/S@MnO2 composite for advanced lithium–sulfur batteries. The delicately designed hybrid architecture can effectively confine LiPSs and obtain high sulfur loading up to 10 mg cm−2, in which the inner carbon microspheres with a large pore volume and large specific surface area can encapsulate high sulfur content, and the outer MnO2 nanosheets, as a catalytic layer, can improve the conversion reaction of LiPSs and suppress the shuttle effect. The thick HPCs/S@MnO2 electrode with 7 mg cm−2 sulfur loading delivers an areal capacity of 4.0 mAh cm−2 at 0.1 C and provides stable cycling stability with a low-capacity decay rate of 0.063 % per cycle after 200 cycles at 0.1 C. Furthermore, a Li–S pouch cell with a capacity of 2.5 A h is fabricated and demonstrates high cycling stability. This work offers a feasible method to build advanced sulfur electrodes with high areal loading and sheds light on their commercial application in high-performance Li–S batteries.

Keywords

• lithium–sulfur batteries
• porous carbon microspheres
• MnO₂ nanosheets
• high sulfur loading
• catalytic conversion