Cationic MOF-Based Cu/Mo Bimetal Doped Multifunctional Carbon Nanofibers As Efficient Catalyst for High Sulfur Loading Lithium-Sulfur Batteries

Abstract

High sulfur loading is the key to achieve high energy density promised by lithium-sulfur (Li-S) batteries. However, serious problems such as low sulfur utilization, poor rate performance and cycle stability have been exposed during the scaling up of the sulfur loading for freestanding cathodes. To address these issues, the adsorption/catalytic ability of high sulfur loading cathode toward polysulfides must be improved. Herein, based on excellent properties of cationic MOFs, we proposed that Cu-Mo bimetallic nanoparticles embedded in multifunctional freestanding nitrogen-doped porous carbon nanofiber (Cu-Mo@NPCN) with efficient catalytic sites and high sulfur loading capacity could be prepared by facile transition metal-based anion exchange of cationic MOFs. And the sulfur embedded in Cu-Mo@NPCN was directly used as freestanding sulfur cathodes, enabling a high areal capacity, good rate performance, and cycling stability even under high sulfur loading. The freestanding Cu-Mo@NPCN/10.3S achieves high areal capacity of 9.3 mA h cm-2 and volumetric capacity of 1163 mA h cm-3 at 0.2 C with a sulfur loading of 10.3 mg cm-2. This work provides new insights into freestanding sulfur cathode engineering for high-performance Li-S batteries and would advance the development of cationic MOF-derived bimetallic catalysts in various energy storage technologies. Figure 1