New cathode materials for rechargeable lithium batteries: The 3-D framework structures Li3Fe2(XO4)(3) (X = P, As)

摘要

Electrochemical insertion of lithium into four Li3Fe2(XO4)(3) polymorphs (X = P or As) with 3-D framework structures was carried out in "Li/LiClO4(PC:DME)/cathode" coin cells, Approximately 2 Li per formula unit could be reversibly inserted into the three different structures, which corresponds to the reduction of all Fe3+ to Fe2+ between 2.5 and 3.5 V vs lithium. The position of the Fe3+/Fe2+ redox couple below the lithium-anode Fermi energy is nearly independent uf the structure and of whether X = P or As, There rs, however, a clear dependence of (i) the shape of the V-cc vs x curves for Li3+xFe2(XO4)(3) and (ii) the charge-discharge rare capabilities on the crystal structure of the cathode material, (C) 1998 Academic Press. [References: 25]