Constructing Heterogeneous Structure in Metal-Organic Framework-Derived Hierarchical Sulfur Hosts for Capturing Polysulfides and Promoting Conversion Kinetics.

Abstract

Lithium-sulfur batteries (LSBs) are still severely blocked by the shuttle of polysulfides (LiPSs), resulting in low sulfur utilization and decreased lifetime. The optimal design of hosts with tailored porous structures and catalytic sites is expected to address this issue. Herein, a Bi/Bi2O3 heterostructure within the metal-organic framework (MOF)-derived sulfur host with a hierarchical structure was elaborated for both serving as sulfur hosts and promoting the redox reaction kinetics of LiPSs. The shuttle effects of LiPSs can be mitigated by the dual functional Bi/Bi2O3 heterostructure enriched in the outer layer of CAU-17-derived carbonic rods, i.e., the effective redox conversion of LiPSs can be realized at the Bi/Bi2O3 heterointerface by the adsorption of LiPSs over Bi2O3 and subsequently catalytic conversion over Bi. Benefiting from these merits, the fabricated LSBs realized a significantly optimized performance, including a high discharge capacity of 740.8 mAh g-1 after 1000 cycles with an ultralow decay rate of 0.022% per cycle at 1 C, a high areal capacity of 6.6 mAh cm-2 after 100 cycles with a sulfur loading of 8.1 mg cm-2, and good performance in pouch cells as well.