The preparation and characterization of iron fluorides polymorphs FeF3·0.33H2O and β-FeF3∙3H2O as cathode materials for lithium-ion batteries. (April 2015)

• Record Type: Journal Article
• Authors: Chen, Chao; Xu, Xiaoping; Chen, Shu; Zheng, Bin; Shui, Miao; Xu, Lingxia; Zheng, Weidong; Shu, Jie; Cheng, Liangliang; Feng, Lin; Ren, Yuanlong
• Is Part Of: Materials research bulletin. Volume 64(2015:Apr.)
• Page Start: 187
• Page End: 193
• Publication Date: 2015-04
• Subjects: A. Fluorides -- B. Chemical synthesis -- C. Electrochemical measurements -- D. Electrochemical properties; Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2014.12.061
• Languages: English
• ISSNs: 0025-5408

Abstract

Graphical abstract: Better rate capability and cycling performance were observed for β-FeF3 ·3H2 O/C prepared by mechano-chemical synthesis. Highlights: A novel mechano-chemical preparation method. The use of NH4 F as starting material. Better electro-chemical performance in the case of β-FeF3 ·3H2 O/C. Abstract: Two kinds of iron fluorides, FeF3 ·0.33H2 O and β-FeF3 ∙3H2 O, have been synthesized by different chemical routes using Fe(NO3 )3 ·9H2 O and NH4 F as precursors and investigated as cathode materials for secondary lithium batteries. β-FeF3 ·3H2 O was obtained via a mechano-chemical process and FeF3 ·0.33H2 O was obtained by a precipitation reaction from ethanol solution. To further improve their electrochemical properties, a ball milling process with carbon has been used to form composites. The fluorides were characterized by X-ray diffraction (XRD), thermal analysis, FTIR spectroscopy, galvanostatic charge/discharge and cyclic voltammetry measurements. The results showed that the as-prepared β-FeF3 ·3H2 O/C exhibited better rate performance and cycling stability. It exhibited an initial discharge capacity of 199.6 mA h g −1 at a current density of 20 mA g −1 in a voltage range of 1.8–4.5 V and still reserved a discharge capacity of about 146.5 mA h g −1 after 10 cycles. Only a capacity loss of 15 mA h g −1 and 7 mA h g −1 was observed when the current density was at 40 mA g −1 and 80 mA g −1, respectively.