Intercalation-type catalyst for non-aqueous room temperature sodium-sulfur batteries

• Published in: Nature communications 2023-10, Vol.14 (1), p.6568-6568, Article 6568
• Main Authors: He, Jiarui, Bhargav, Amruth, Su, Laisuo, Charalambous, Harry, Manthiram, Arumugam
• Format: Article
• Language: English
• Subjects: 147/28; 639/301/299/891; 639/4077/4079/891; 639/638/161/891; 639/638/675; Active sites; Alternative energy sources; Ambient temperature; Catalysts; Catalytic activity; Conversion; Electrode materials; Electrodes; Electrolytes; Graphene; Humanities and Social Sciences; Intercalation; Lithium; Lithium-ion batteries; Mass spectrometry; Mass spectroscopy; Molybdenum compounds; multidisciplinary; Polysulfides; Rechargeable batteries; Room temperature; Science; Science (multidisciplinary); Secondary ion mass spectrometry; Sodium; Sodium sulfide; Sodium sulfur batteries; Specific energy; Sulfur; Synchrotrons; Tellurides; X-ray diffraction
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-42383-3

Ambient-temperature sodium-sulfur (Na-S) batteries are potential attractive alternatives to lithium-ion batteries owing to their high theoretical specific energy of 1,274 Wh kg −1 based on the mass of Na 2 S and abundant sulfur resources. However, their practical viability is impeded by sodium polysulfide shuttling. Here, we report an intercalation-conversion hybrid positive electrode material by coupling the intercalation-type catalyst, MoTe 2 , with the conversion-type active material, sulfur. In addition, MoTe 2 nanosheets vertically grown on graphene flakes offer abundant active catalytic sites, further boosting the catalytic activity for sulfur redox. When used as a composite positive electrode and assembled in a coin cell with excess Na, a discharge capacity of 1,081 mA h g s −1 based on the mass of S with a capacity fade rate of 0.05% per cycle over 350 cycles at 0.1 C rate in a voltage range of 0.8 to 2.8 V is realized under a high sulfur loading of 3.5 mg cm −2 and a lean electrolyte condition with an electrolyte-to-sulfur ratio of 7 μL mg −1 . A fundamental understanding of the electrocatalysis of MoTe 2 is further revealed by in-situ synchrotron-based operando X-ray diffraction and ex-situ time-of-flight secondary ion mass spectrometry. Sodium-sulfur batteries show potential as attractive alternatives to Li-ion batteries due to their high energy density but practicality is hampered by sodium polysulfide issues. Here, the authors introduce an intercalation-type catalyst MoTe2 to improve the redox kinetics in Na-S batteries.