טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentVera Naschitz
SubjectSynthesis and Characterization of Novel Super Iron Fe(VI)
Compounds
DepartmentDepartment of Chemistry
Supervisors Professor Emeritus Yarnitzky Chaim (Deceased)
Mr. Licht Stuart


Abstract

The synthesis and physical chemical characterization of Fe(VI) salts, exhibiting unusually facile charge transfer applicable  to the high power domain of alkaline batteries, are probed. A rapid synthesis of high stability BaFeO4 is demonstrated, utilizing all solid state reactants and eliminating several synthetic procedural steps. Synthesis procedures for SrFeO4 and mixed salts containing barium and strontium cations, SrxBa(1-x)FeO4, are also presented. The synthesized salts were analyzed by titrimetric, ICP, FTIR and XRD analytical techniques. The first x-ray diffraction and IR spectra of SrFeO4 are presented and compared to known spectra of K2FeO4 and BaFeO4.  Electrochemical storage cells, prepared with this new cathode, exhibit high discharge energies. The solubility of BaFeO4 and K2FeO4 in aqueous or non-aqueous electrolytes has also been investigated.

It was found that several solid phase modifiers like Co2O3 or coating with 1% MnO2 can significantly affect the electrochemical characteristics of the Fe(VI) cathode, via a electro-catalytic mechanism. The addition of In2O3 decreases the reversible charging potential of the Fe(VI) cathode.

Alkaline Fe(VI) cathodic charge transfer was found to be significantly improved by the addition of  several percent of AgO. The capacity of a cell employing the Fe(VI) cathode and a Zn anode is twice the capacity of a Zn/BaFeOcell and exceeds that of the conventional high power Zn/MnOalkaline battery by a factor of 3-5.