A highly fluorinated lithium iron phosphate with interpenetrating lattices: electrochemistry and ionic conductivity. Issue 37 (14th September 2017)

• Record Type: Journal Article
• Authors: Yaghoobnejad Asl, Hooman; Ghosh, Kartik; Choudhury, Amitava
• Is Part Of: Dalton transactions. Volume 46:Issue 37(2017)
• Page Start: 12588
• Page End: 12596
• Publication Date: 2017-09-14
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c7dt02202f
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A fluorinated iron phosphate with interpenetrating lattices containing large channels filled with lithium ions has been synthesized in low-melting flux. Abstract : Li5 Fe2 PO4 F8, a new member of the family of alkali transition metal fluorophosphates, has been synthesized and characterized using single-crystal X-ray diffraction, 57 Fe Mössbauer spectroscopy and magnetic susceptibility measurements. The existence of an infinite {–[PO4 (FeF4 )2 ]–}∞ tetrahedral network in an inter-penetrated diamond lattice, along with the presence of seven unique Li sites, presents interesting structural features of this structure-type for energy storage applications. The initial results of (de)lithiation reveal that a relatively low fraction of theoretical capacity may be utilized reversibly (0.2 Li + ion per formula unit), possibly due to the lack of available free volume for Li + insertion. The high Li content and the existence of large channels in all 3-dimensions of space also offer opportunities to study this material as a candidate for solid-state electrolytes. The results from electro-impedance measurements reveal the reasonable activation energy of Li diffusion (0.70 eV), which is also supported by theoretical calculations.