Abstract: A positive electrode active material, including a boron-doped Prussian blue analog; and the Prussian blue analog has a chemical formula of AaMbM?c(CN)6·dH2O, in which A includes at least one of an alkali metal cation, an alkaline earth metal cation, Zn2+, and Al3+, M and M? each independently includes at least one of Ni ion, Cu ion, Fe ion, Mn ion, Co ion, and Zn ion, and H2O is coordination water, 0<a?2, 0<b?1, 0<c?1, 0?d?2; and relates to a preparation method, a secondary battery, and an electrical device. The stability of the positive electrode active material is improved, and thus improving a cycle performance of the corresponding secondary battery; and the preparation method of the positive electrode active material is simple in operation, mild in reaction conditions, and convenient for industrial application.

Abstract: The present application provides a positive electrode active material which may be in a particulate form and comprise a compound represented by Formula 1: NaxAyM1[M2(CN)6]?·zH2O??Formula 1 wherein, A is selected from at least one of an alkali metal element and an alkaline earth metal element, and the ionic radius of A is greater than the ionic radius of sodium; M1 and M2 are each independently selected from at least one of a transition metal element, 0<y?0.2, 0<x+y?2, 0<??1, and 0?z?10; and the particles of the positive electrode active material may have a gradient layer in which the content of the A element decreases from the particle surface to the particle interior.

Abstract: A positive electrode active material is granular and comprises a compound represented by formula 1: (NaxAy)a?bM1[M2(CN)6]?, wherein A is selected from at least one of alkali metal elements and has an ionic radius greater than that of sodium, M1 and M2 are each independently selected from at least one of transition metal elements, 0<y?0.2, 0<x+y?2, 0???1, a+b=2, 0.85?a?0.98, (represents a vacancy, and b represents the number of vacancies; and when the positive electrode active material is dissolved, at a temperature of 20° C., into an aqueous solution having a concentration of 5 g/100 g water, a pH value of the aqueous solution is in a range of 7.6 to 8.5. The positive electrode active material has good cycling and rate performance, and a high specific capacity.

Abstract: The present application provides a positive electrode active material which may be in a particulate form and comprise a compound represented by Formula 1: NaxAyM1[M2(CN)6]?·zH2O??Formula 1 wherein, A is selected from at least one of an alkali metal element and an alkaline earth metal element, and the ionic radius of A is greater than the ionic radius of sodium; M1 and M2 are each independently selected from at least one of a transition metal element, 0<y?0.2, 0<x+y?2, 0<??1, and 0?z?10; and the particles of the positive electrode active material may have a gradient layer in which the content of the A element decreases from the particle surface to the particle interior.