Open-framework iron(II) phosphate-oxalate as anode material for Li-ion batteries.

The iron(II) phosphate-oxalate compound, namely (C₄H₁₂N₂)[Fe₄(HPO₄)₂(C₂O₄)₃] (abbreviated as FPC), was synthesized and studied as anode material for lithium-ion batteries (LIBs). The structure of FPC was characterized by single-crystal X-ray diffraction. The FPC anode material gives a reversible capacity of 966.1 mAh g⁻¹ after 400 cycles and good rate capability of 383.1 mAh g⁻¹ at 2 A g⁻¹. The lithium storage mechanism for FPC was analyzed. The results suggest that the electrochemical activity of FPC arises from the conversion reaction accompanied by the formation of Li₃PO₄ after lithiation. The in situ generation of ion conductive Li₃PO₄ and the redox process between FePO₄ and Fe contribute to the good rate capability and cycling stability of the FPC anode. [ABSTRACT FROM AUTHOR]