In operando x-ray studies of high-performance lithium-ion storage in keplerate-Type polyoxometalate anodes

Chia Ching Lin, Chi Ting Hsu, Wenjing Liu, Shao Chu Huang, Ming Hsien Lin, Ulrich Kortz, Ali S. Mougharbel, Tsan Yao Chen, Chih Wei Hu, Jyh Fu Lee, Chun Chieh Wang, Yen Fa Liao, Lain Jong Li, Linlin Li, Shengjie Peng, Ulrich Stimming, Han Yi Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)40296-40309
Number of pages14
JournalACS Applied Materials and Interfaces
Volume12
Issue number36
DOIs
StatePublished - Sep 9 2020

Keywords

  • anode materials
  • charge-storage mechanism
  • electrode
  • lithium-ion batteries
  • polyoxometalate

ASJC Scopus subject areas

  • General Materials Science

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