Lithium intercalation mechanism into FeF3·0.5H2O as a highly stable composite cathode material

Ghulam Ali, Ji Hoon Lee, Wonyoung Chang, Byung Won Cho, Hun Gi Jung, Kyung Wan Nam, Kyung Yoon Chung

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

The growing demand for lithium-ion batteries (LIBs) requires investigation of high-performance electrode materials with the advantages of being environmentally friendly and cost-effective. In this study, a nanocomposite of open-pyrochlore-structured FeF3·0.5H2O and reduced graphene oxide (RGO) is synthesized for use as a high-performance cathode in LIBs, where RGO provides high electrical conductivity to the composite material. The morphology of the composite shows that FeF3·0.5H2O spheres are embedded into RGO layers and high-resolution TEM image shows that those spheres are composed of primary nanoparticles with a size of ∼5 nm. The cycling performance indicates that the composite electrode delivers an initial high discharge capacity of 223 mAh g-1 at 0.05 C, a rate capability up to a high C-rate of 10 C (47 mAh g-1) and stable cycle performance at 0.05 C (145 mAh g-1 after 100 cycles) and 0.2 C (93 mAh g-1 after 100 cycles) while maintaining high electrochemical reversibility. Furthermore, the responsible electrochemical reaction is investigated using in-situ XRD and synchrotron-based X-ray absorption spectroscopy (XAS), and the XRD results show that FeF3·0.5H2O transitions to an amorphous-like phase through a lithiation process. However, a reversible oxidation change of Fe3+→Fe2+ is identified by the XAS results.

Original languageEnglish
Article number42237
JournalScientific Reports
Volume7
DOIs
StatePublished - 7 Feb 2017

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