Positive Electrode Active Material for Secondary Battery

摘要

Provided is a cathode active material for a secondary battery, specifically, a cathode active material for a secondary battery including sodium transition metal pyrophosphate satisfying Na3.12−x2Acx1M1ay1M2by2 (P2O7) z, which has an advantage of structural stability due to a strong P—O bond of sodium transition metal phosphate having an olivine structure, and also performs proper intercalation and deintercalation of Na ions having a large ion radius, thereby significantly improving reversibility during charging and discharging, and a charge and discharge rate.

主权项

1. A cathode active material for a secondary battery comprising sodium transition metal pyrophosphate satisfying following Chemical Formula 1:
Na3.12−x2Acx1M1ay1M2by2(P2O7)2   [Chemical Formula 1] wherein Ac is one or two or more elements (A) selected from the group consisting of alkali metals and alkali earth metals having a valence of c of 1 or 2; x1 is a real number of 0≦x1≦0.5; x2 is a product of c and x1 (x2=x1*c); M1a is one or two or more elements (M1) selected from the group consisting of transition metals and Groups 12 to 14 elements having a valence of a; M2b is one or two or more elements (M2) selected from the group consisting of transition metals and Groups 12 to 14 elements having a valence of b; a and b are identical to or different from each other, and independently of each other, an integer of 2 to 4; and y1 is a real number of 0