Electrochemically Active Molybdenum Phosphate with Open-Framework Structure

Abstract

Somewhat less investigated, lithium ion containing molybdenum phosphate compounds are synthesized via simple template free hydrothermal method. Single-crystal X-ray diffraction (SCXRD) study reveals that the compounds Li0.89Mo2O1.89F0.11(PO4)2(H2PO4)·xH2O (x ?1) and Li3Mo2O2(PO4)3·xH2O (x ?1) crystallize in monoclinic C2/m and C2/c space group, respectively. The structures are built of alternate corner-sharing of MoO6 octahedra and PO4 tetrahedra forming layers, which are pillared by phosphate groups creating a 3D framework with channels. These channels host Li-ions and have the potential for further intercalation of alkali ions. When heated at 200 °C, both the compounds go through structural rearrangements due to the removal of crystal water which results in an anhydrous phase with the same structural arrangement. When studied as Li-ion intercalation cathode, the anhydrous phase of Li0.89Mo2O1.89F0.11(PO4)2(H2PO4)·xH2O (x ?1) achieves 79.36 mAh g?1 capacity upon charging corresponding to the removal of ?1 Li ion from the structure. The subsequent discharge capacity corresponds to 2.88 moles of Li ion insertion to the structure. Additionally, Na ions could be reversibly intercalated when cycled between 1.5 and 4 V. Besides electrochemistry, Fourier-transformation infrared, X-ray photoelectron spectroscopy, and thermogravimetric analysis are performed to confirm the presence of water and thermal stability of the materials.

Department(s)

Chemistry and Biochemistry

Document Type

Article

DOI

10.1002/zaac.202500140

Keywords

Li-ion battery, molybdenum phosphate, multielectron redox, Na-ion battery, polyanion cathode

Publication Date

12-10-2025

Journal Title

Zeitschrift Fur Anorganische Und Allgemeine Chemie

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