One-pot preparation of structurally tunable mesoporous hollow carbon spheres and their application for lithium‑sulfur battery with high sulfur content

Abstract

Hollow carbon nanomaterials as sulfur hosts have been investigated extensively for lithium‑sulfur (LiS) battery. Herein, we report the preparation of structurally tunable mesoporous hollow carbon spheres (MHCs) by a simple one-pot self-assembly method. The structural parameters (specific surface area, pore capacity, pore size, and cavity) of the MHCs were adjusted by varying the concentration of the reactants. Three representative MHCs were characterized in detail, and the reasons for their formation were explained. Among them, the optimized MHC features a high specific surface area (1547.9 m2 g−1), large pore capacity (2.04 cm3 g−1), moderate pore size (∼ 6 nm), and internal cavity (r2/r1 = 0.62), which can meet the requirements of high sulfur loading, good carbon/sulfur contact, sufficient buffer space, and fast electron/ion transport channels. Consequently, the optimized MHC@S cathode exhibited improved electrochemical properties (maintaining a capacity of 484.7 mAh g−1 after 500 cycles at 0.5C with a decay rate of 0.068 %) under the condition of high sulfur content of 90.02 wt% and the electrolyte/sulfur ratio of 10 μL mg−1. Moreover, the raw materials are cost-effective, and the process is simple to operate without requiring expensive equipment. This study provides a promising candidate for carbon-based materials as sulfur hosts in practical LiS battery.