Synthesis and electrochemical properties of novel LiFeTiO4 and Li2FeTiO4 polymorphs with the CaFe2O4-type structures

Academic Article

Abstract

  • The new LiFeTiO4 polymorph with the CaFe2O4-type (CF) crystal structure was synthesized via ion exchange from NaFeTiO4. Due to the presence of tunnels sufficiently large to accommodate additional Li+ ions, CF-LiFeTiO4 was studied as a model compound for potential cathode material utilizing Fe2+/Fe3+ (on Li intercalation) as well as Fe3+/Fe4+ (on Li deintercalation) redox couples. Chemical and electrochemical Li intercalation preserves the structural motif of CF-LiFeTiO4 and results in Li2FeTiO4 compound. The electrochemical cycling of CF-LiFeTiO4 vs. Li occurs between 2 and 2.3 V with an initial specific capacity of 148 mAh g-1. High Li+ ionic conductivity in the compound is suggested based on the interconnection of Li+ bond valence sum isosurfaces at a bond valence sum value of 1.0. Chemical Li deintercalation from CF-LiFeTiO4 results in compound decomposition without Fe4+ formation, as confirmed by Mössbauer spectroscopy.
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    Digital Object Identifier (doi)

    Author List

  • Bruno SR; Blakely CK; Clapham JB; Davis JD; Bi W; Alp EE; Poltavets VV
  • Start Page

  • 396
  • End Page

  • 403
  • Volume

  • 273