Conditions Extrêmes et Matériaux : Haute Température et Irradiation

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R.Essehli, A.Faik, B.El Bali, M.Naji, K.Eddahaoui, S.Benmokhtar, Y.R.Zong, M.Dusek, 'Iron Titanium Phosphate as High Specific Charge Electrode Materials For Lithium ion Batteries', J. Alloy Compd. 585 434-441 (2014) doi:10.1016/j.jallcom.2013.09.093

Two iron titanium phosphates, Fe0.5TiOPO4 and Fe0.5Ti2(PO4)3, were prepared and their structure and electrochemical performances were compared. The electrochemical measurements of Fe0.5TiOPO4 as an anode of a lithium ion cell showed that upon the first discharge down to 0.5 V, the cell delivered a capacity of 560 mAh/g, corresponding to the insertion of 3.5 Li per formula unit Fe0.5TiOPO4. The Nasicon kind phosphate Fe0.5Ti2(PO4)3 consists of a three-dimensional network made of corners and edges sharing [TiO6] and [FeO6] octahedra and [PO4] tetrahedra leading to the formation of trimmers [FeTi2O12]. The first discharge of lithium ion cells based on Fe0.5Ti2(PO4)3 materials showed electrochemical activity of Ti4+/Ti3+ and Fe2+/Fe0 couples in the 2.5-1 V region. Below this voltage, the discharge profiles are typical of phosphate systems where Li3PO4 is a product of the electrochemical reaction with lithium; moreover, the electrolyte solvent is reduced. Capacities as high as 1100 mAh g−1 can be obtained at deep discharge. However, there is an irreversible capacity loss in Fe0.5Ti2(PO4)3 due to the occurrence of insulating products as Li3PO4 and a solid electrolyte interface.