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Mixed Anionic and Cationic Redox Chemistry in a Tetrathiomolybdate Amorphous Coordination Framework
Author(s) -
Zhu Qi,
Wang Jiande,
Liu Xuelian,
Ebejer Neil,
Rambabu Darsi,
Vlad Alexandru
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202004587
Subject(s) - redox , chemistry , electrochemistry , cationic polymerization , oxidation state , inorganic chemistry , sulfide , ionic bonding , amorphous solid , lithium (medication) , x ray photoelectron spectroscopy , ionic conductivity , ion , electrode , crystallography , chemical engineering , metal , polymer chemistry , organic chemistry , medicine , engineering , electrolyte , endocrinology
Abstract We report the electrochemistry of a hitherto unexplored Na 2 MoS 4 phase as a conversion electrode material for Na‐ and Li‐ion batteries. The material adopts an amorphous coordination polymer structure with mixed Mo and S valences. XPS and XRD analysis reveal a complex interplay between Mo and S redox chemistry, while excluding the formation of free sulfur, lithium sulfide, or other crystalline phases. Na 2 MoS 4 behaves as a mixed ionic–electronic conductor, with electronic conductivity of 6.1×10 −4 S cm −1 , that permits carbon‐free application in an electrochemical cell. A reversible capacity of up to 500 mAh g −1 was attained, corresponding to a five‐electron redox exchange, with species ranging from (highest oxidized state) to 5 MoS 4 > (lowest oxidized state). This study emphasizes the excellent charge‐storage performances of Na 2 MoS 4 for Li‐ or Na‐ion batteries, and enriches the emerging library and knowledge of sulfide phases with mixed anionic and cationic redox properties.