POSITIVE ELECTRODE ACTIVE MATERIAL AND HYBRID ION BATTERY

The main object of the present invention is to provide a cathode active material which is used for a hybrid ion battery of Li ions and Na ions, and operates at a high potential. The present invention solves the problem by providing a cathode active material used for a hybrid ion battery of Li ions and Na ions, comprising an Na 4 M 3 (PO 4 ) 2 P 2 O 7 crystal phase (M is at least one kind of Ni, Co, Mn, Fe, V, Cr, Cu and Zn).