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Lookup NU author(s): Professor Ulrich Stimming
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Copyright © 2020 American Chemical Society.Polyoxometalates (POMs) have emerged as potential anode materials for lithium-ion batteries (LIBs) owing to their ability to transfer multiple electrons. Although POM anode materials exhibit notable results in LIBs, their energy-storage mechanisms have not been well-investigated. Here, we utilize various in operando and ex situ techniques to verify the charge-storage mechanisms of a Keplerate-Type POM Na2K23{[(MoVI)MoVI5O21(H2O)3(KSO4)]12 [(VIVO)30(H2O)20(SO4)0.5]}·ca200H2O ({Mo72V30}) anode in LIBs. The {Mo72V30} anode provides a high reversible capacity of up to â 1300 mA h g-1 without capacity fading for up to 100 cycles. The lithium-ion storage mechanism was studied systematically through in operando synchrotron X-ray absorption near-edge structure, ex situ X-ray diffraction, ex situ extended X-ray absorption fine structure, ex situ transmission electron microscopy, in operando synchrotron transmission X-ray microscopy, and in operando Raman spectroscopy. Based on the abovementioned results, we propose that the open hollow-ball structure of the {Mo72V30} molecular cluster serves as an electron/ion sponge that can store a large number of lithium ions and electrons reversibly via multiple and reversible redox reactions (Mo6+ â "Mo1+ and V5+/V4+â "V1+) with fast lithium diffusion kinetics (DLi+: 10-9-10-10 cm2 s-1). No obvious volumetric expansion of the microsized {Mo72V30} particle is observed during the lithiation/delithiation process, which leads to high cycling stability. This study provides comprehensive analytical methods for understanding the lithium-ion storage mechanism of such complicated POMs, which is important for further studies of POM electrodes in energy-storage applications.
Author(s): Lin C-C, Hsu C-T, Liu W, Huang S-C, Lin M-H, Kortz U, Mougharbel AS, Chen T-Y, Hu C-W, Lee J-F, Wang C-C, Liao Y-F, Li L-J, Li L, Peng S, Stimming U, Chen H-Y
Publication type: Article
Publication status: Published
Journal: ACS Applied Materials and Interfaces
Year: 2020
Volume: 12
Issue: 36
Pages: 40296-40309
Print publication date: 09/09/2020
Online publication date: 25/08/2020
Acceptance date: 02/04/2016
ISSN (print): 1944-8244
ISSN (electronic): 1944-8252
Publisher: American Chemical Society
URL: https://doi.org/10.1021/acsami.0c09344
DOI: 10.1021/acsami.0c09344
PubMed id: 32841558
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