title: An FeF(3)·0.5H2O polytype: a microporous framework compound with intersecting tunnels for Li and Na batteries.
abstract: To improve the energy/power density of energy storage materials, numerous efforts have focused on the exploration of new structure prototypes, in particular metal-organic fameworks, Prussian blue analogues, open-framework oxides, and polyanion salts. Here we report a novel pyrochlore phase that appears to be useful as a high-capacity cathode for Li and Na batteries. It is an iron fluoride polymorph characterized by an intersecting tunnel structure, providing the space for accommodation and transport of Li and Na ions. It is prepared using hydrolyzable ionic liquids, which serve as reaction educts and structure-directing agents not only as far as the chemical structure is concerned but also in terms of morphology (shape, defect structure, electrode network structure). A capacity higher than 220 mA h g(-1) (for Li and Na storage) and a lifetime of at least 300 cycles (for Li storage) are demonstrated.
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China. chilinli@mail.sic.ac.cn
authors.forename: Chilin
authors.initials: C
authors.lastname: Li
authors.forename: Congling
authors.initials: C
authors.lastname: Yin
authors.forename: Lin
authors.initials: L
authors.lastname: Gu
authors.forename: Robert E
authors.initials: RE
authors.lastname: Dinnebier
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Mu
authors.forename: Peter A
authors.initials: PA
authors.lastname: van Aken
authors.forename: Joachim
authors.initials: J
authors.lastname: Maier