Open AccessOperando Observations of Reversible α-BiF3 Conversion in Liquid Electrolyte by Synchrotron Radiation Diffraction and 7Li Nuclear Magnetic Resonance
Author(s) -
Mitsuo Kawasaki,
Hisao Kiuchi,
Kei Shimoda,
Gentaro Kano,
Hiroyuki Fujimoto,
Zempachi Ogumi,
Takeshi Abe
Publication year - 2020
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/abad6d
Subject(s) - synchrotron radiation , electrolyte , synchrotron , materials science , electrode , diffraction , chemistry , analytical chemistry (journal) , optics , physics , chromatography
The electrochemically-driven conversion reaction of BiF 3 with Li + ions is of interest for potential application as a positive electrode system in conversion type rechargeable batteries. Here, we use synchrotron radiation diffraction and 7 Li nuclear magnetic resonance (NMR) for complementary operando observations of reversible or quasi-reversible conversion reactions of α -BiF 3 nanocomposite electrode at room temperature. The nanocomposite electrode was fabricated by ball milling and subsequent heat treatments. A pronounced XRD peak broadening indicated a disordered fine crystalline state in the electrode. The operando synchrotron radiation diffraction measurements revealed a quasi-reversible smooth crystallographic transformation between α -BiF 3 and metallic Bi. The operando 7 Li NMR measurement quantitatively showed reversible conversion reactions. The series of in-situ 7 Li NMR spectra contained sharp signals from Li + ions in the electrolyte and a broad signal associated with a solid phase of LiF. These signals followed a stoichiometric relationship that conformed to a three-electron BiF 3 conversion pathway.