Scientific Reports (Dec 2019)

Spin polarization in the phase diagram of a Li–Fe–S system

  • Tsuyoshi Takami,
  • Tomonari Takeuchi,
  • Toshiharu Fukunaga

DOI
https://doi.org/10.1038/s41598-019-56244-x
Journal volume & issue
Vol. 9, no. 1
pp. 1 – 7

Abstract

Read online

Abstract Divalent and trivalent states of Fe ions are known to be stable in inorganic compounds. We focus a novel Li x FeS5 cathode, in which the Li content (x) changes from 2 to 10 by an electrochemical technique. As x increases from 2, a Pauli paramagnetic conductive Li2FeS5 phase changes into a superparamagnetic insulating Li10FeS5 phase. Density functional theory calculations suggest that Fe+ ions in a high-x phase are responsible for ferromagnetic spin polarization. Reaching the monovalent Fe ion is significant for understanding microscopic chemistry behind operation as Li-ion batteries and the original physical properties resulting from the unique local structure.