Abstract: A method for manufacturing an active material, capable of improving the discharge capacity of a lithium ion secondary battery is provided. The method for manufacturing an active material according to the present invention includes a first step of heating a mixture solution including a lithium source, a phosphate source, a vanadium source, and water under pressure to generate a precursor in the mixture solution, and adjusting the pH of the mixture solution including the precursor to be 6 to 8; and a second step of heating the precursor at 425 to 650° C. after the first step to generate an active material.

Abstract: An active material having high capacity and excellent charging/discharging cycle durability at high potential is provided. The active material has a layered structure and is represented by the following composition formula (1): LiyNiaCobMncMdOxFz1Pz2 ??(1) wherein the element M is at least one element selected from the group consisting of Al, Si, Zr, Ti, Fe, Mg, Nb, Ba and V, and 1.9?(a+b+c+d+y)?2.1, 1.0?y?1.3, 0<a?0.3, 0?b?0.25, 0.3?c?0.7, 0?d?0.1, 0.07?z1?0.15, 0.01?z2?0.1, and 1.9?(x+z1)?2.1 are satisfied.

Abstract: Active material is obtained by sintering a precursor, has a layered structure and is represented by the following formula (1). The temperature at which the precursor becomes a layered structure compound in its sintering in atmospheric air is 450° C. or less. Alternatively, the endothermic peak temperature of the precursor when its temperature is increased from 300° C. to 800° C. in its differential thermal analysis in the atmospheric air is 550° C. or less. LiyNiaCobMncMdOxFz??(1) In formula (1), the element M is at least one of Al, Si, Zr, Ti, Fe, Mg, Nb, Ba, and V and 1.9?(a+b+c+d+y)?2.1, 1.0?y?1.3, 0<a?0.3, 0?b?0.25, 0.3?c?0.7, 0?d?0.1, 1.9?(x+z)?2.0, and 0?z?0.15 are satisfied.