Energizing sulfur chemistry: Synergistic modulation of oxygen vacancies and heterointerface in MoO 2– x -Mo 2 C@NC for long-lasting lithium-sulfur batteries

Le résumé fourni par la source

The practical deployment of lithium-sulfur (Li-S) batteries is impeded by severe polysulfide shuttle effects and sluggish redox kinetics. The use of heterostructures as catalysts in sulfur hosts is expected to improve the electrochemical performance of Li-S batteries. However, single heterostructures still suffer from the fatal problems of few active sites and high charge transfer barriers. Herein, defect-engineered MoO2–x-Mo2C@NC (NC is the abbreviation form of nitrogen-doped carbon) is designed as an efficient electrocatalyst to adjust the surface properties and electron distribution of the heterostructure by introducing a defective structure into the heterostructure, thereby enhance active site exposure. The d-orbitals of Mo2C facilitate strong interactions with the p-electrons of MoO2, enabling efficient electron transfer between reactants and active sites. DFT calculations confirm the interaction of the d orbitals of Mo2C with the p electrons in the MoO2 material, effectively lowering the reaction energy barrier. As a result, the S/MoO2–x-Mo2C@NC exhibits remarkable cycle stability, retaining a specific capacity of 714 mAh·g–1 after 500 cycles at 0.5 C. This work provides insights into defect-driven heterostructure design for advanced Li-S batteries.

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