Reaction Mechanism of the Sn 2 Fe Anode in Lithium-Ion Batteries.

Autor: Dong Z; Institute for Materials Research and Department of Chemistry, Binghamton University, Binghamton, New York 13902-6000, United States., Wang Q; Institute for Materials Research and Department of Chemistry, Binghamton University, Binghamton, New York 13902-6000, United States., Zhang R; Institute for Materials Research and Department of Chemistry, Binghamton University, Binghamton, New York 13902-6000, United States., Chernova NA; Institute for Materials Research and Department of Chemistry, Binghamton University, Binghamton, New York 13902-6000, United States., Omenya F; Institute for Materials Research and Department of Chemistry, Binghamton University, Binghamton, New York 13902-6000, United States., Ji D; Institute for Materials Research and Department of Chemistry, Binghamton University, Binghamton, New York 13902-6000, United States., Whittingham MS; Institute for Materials Research and Department of Chemistry, Binghamton University, Binghamton, New York 13902-6000, United States.
Jazyk: angličtina
Zdroj: ACS omega [ACS Omega] 2019 Dec 18; Vol. 4 (27), pp. 22345-22355. Date of Electronic Publication: 2019 Dec 18 (Print Publication: 2019).
DOI: 10.1021/acsomega.9b02417
Abstrakt: Sn 2 Fe anode materials were synthesized by a solvothermal route, and their electrochemical performance and reaction mechanism were evaluated. The structural evolution in the first two lithium cycles was investigated by X-ray absorption spectroscopy (XAS), synchrotron X-ray diffraction (XRD), and magnetic studies. In the first cycle, progressive alloying of Sn with Li accompanied by metallic iron displacement occurs upon lithiation, and the delithiation proceeds by Li x Sn dealloying and recovery of the Sn 2 Fe phase. In the second cycle, both XRD and XAS identify Li-Sn alloying at earlier lithiation stages than in the first cycle, with low-Li-content alloys evident in the beginning of the lithiation process. In the fully lithiated state, XAS analysis reveals higher coordination numbers in both the Li x Sn and Fe phases, which points toward more complete reaction and higher crystallinity of the products. Upon second delithiation, the Sn 2 Fe phase is generally reformed as evidenced by XRD. However, XAS indicates somewhat reduced Sn-Fe coordination and shorter Fe-Fe distance, which indicates incomplete reconversion and metallic Fe retention, which is also evident in the magnetic studies. Thus, a combination of long-range (XRD, magnetic) and local (XAS) techniques has revealed differences between the first and the second Li cycles relevant to the understanding of the capacity fading mechanisms.
Competing Interests: The authors declare no competing financial interest.
(Copyright © 2019 American Chemical Society.)
Databáze: MEDLINE
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