| abstract |
Disclosed is a positive electrode active material for a sodium ion secondary battery, which is excellent in diffusing property, structural stability and cycle characteristics of an alkali ion, and a method of synthesizing the same. A positive electrode active material for a sodium secondary battery comprises at least one transition metal element selected from the group consisting of Na x M y P 2 O 7 wherein M is at least one element selected from Cr, Fe, Mn, Co, and Ni, x? 2.10 and y is 0.95? y? 1.60). The positive electrode active material preferably forms a crystal structure belonging to any one of the three eutectic space groups P1 and P1-. |