PYROPHOSPHATE COMPOUND AND METHOD FOR PRODUCING SAME

To provide a positive electrode active material containing a pyrophosphate compound, ensuring that mixing of impurities is easily prevented to facilitate the synthesis and a high capacity battery is obtained, and a lithium ion battery using the positive electrode material. That is, the present invention relates to a pyrophosphate compound represented by the formula: Li 2 M 1-x Fe x P 2 O 7 (wherein M represents one or more elements selected from Mn, Zr, Mg, Co, Ni, V and Cu, and 0.3‰¤x‰¤0.9).