A positive electrode material for a secondary battery, wherein the positive electrode material includes a triclinic crystal structure and is represented by Li.sub.4+x(Fe.sub.1zM.sub.z).sub.40.5x(P.sub.2O.sub.7).sub.3, where 0.65x0.75, 0.0<z0.7, and M represents a divalent metal other than Fe.

Flame retardant polymer compositions comprising certain thermally stable salts of pyrophosphonic acid as flame retardant materials, which flame retardant materials comprise one or more than one metals, are prepared and have excellent flame retardant activity.

Flame retardant polymer compositions comprising certain thermally stable salts of pyrophosphonic acid as flame retardant materials, which flame retardant materials comprise one or more than one metals, are prepared and have excellent flame retardant activity.

Provided are a positive electrode active material composition, a positive electrode plate, a secondary battery, a battery module, a battery pack, and an electric device. In particular, the present application provides a positive electrode active material composition, including a positive electrode active material and a dispersant. The positive electrode active material composition of the present application can improve the poor dispersion of the positive electrode active material powder and the high viscosity of the slurry during the preparation of the positive electrode slurry, and further improve flexibility of the positive electrode plate.

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 Na.sub.3.12x2A.sup.c.sub.x1M.sub.1.sup.a.sub.y1M.sub.2.sup.b.sub.y2 (P.sub.2O.sub.7).sub.z, which has an advantage of structural stability due to a strong PO 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.

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 Na.sub.3.12x2A.sup.c.sub.x1M.sub.1.sup.a.sub.y1M.sub.2.sup.b.sub.y2 (P.sub.2O.sub.7).sub.z, which has an advantage of structural stability due to a strong PO 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.

A nickel hydrogen battery configured to suppress a decrease in battery voltage. The battery comprises a cathode containing a cathode active material, an anode containing an anode active material, and an electrolyte layer in contact with the cathode and the anode. The cathode active material contains H.sub.2NiP.sub.2O.sub.7 having a crystal structure including at least one NiO.sub.6 octahedron and at least one PO.sub.4 tetrahedron.

A nickel hydrogen battery configured to suppress a decrease in battery voltage. The battery comprises a cathode containing a cathode active material, an anode containing an anode active material, and an electrolyte layer in contact with the cathode and the anode. The cathode active material contains H.sub.2NiP.sub.2O.sub.7 having a crystal structure including at least one NiO.sub.6 octahedron and at least one PO.sub.4 tetrahedron.

Provided is an anode active material including a transition metal-pyrophosphate of Chemical Formula 1 below:
M.sub.2P.sub.2O.sub.7<Chemical Formula 1> where M is any one selected from the group consisting of titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), palladium (Pd), and silver (Ag), or two or more elements thereof. Since the anode active material of the present invention is stable and has excellent conversion reactivity while including only transition metal and phosphate without using lithium in which the price thereof is continuously increased, the anode active material of the present invention may improve capacity characteristics.

Provided is an anode active material including a transition metal-pyrophosphate of Chemical Formula 1 below:
M.sub.2P.sub.2O.sub.7<Chemical Formula 1> where M is any one selected from the group consisting of titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), palladium (Pd), and silver (Ag), or two or more elements thereof. Since the anode active material of the present invention is stable and has excellent conversion reactivity while including only transition metal and phosphate without using lithium in which the price thereof is continuously increased, the anode active material of the present invention may improve capacity characteristics.