摘要：Divalent and trivalent states of Fe ions are known to be stable in inorganic compounds. We focus a novel Li x FeS 5 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 Li 2 FeS 5 phase changes into a superparamagnetic insulating Li 10 FeS 5 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.
