| CPC C01G 53/42 (2013.01) [H01M 10/0525 (2013.01)] | 9 Claims |

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1. A method of manufacturing a positive electrode active material for a lithium ion secondary battery comprising:
a mixing step of mixing a lithium-nickel composite oxide, which is a starting material, with a tungsten compound powder without lithium, while being heated, to prepare a tungsten mixture;
a heat treatment step of heat-treating the tungsten mixture,
wherein the lithium-nickel composite oxide contains lithium (Li), nickel (Ni), and an element M
wherein, the element M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti, Co, and Al,
wherein, in the starting material, a ratio of number of tungsten atom to a total number of nickel and the element M atoms contained in the lithium-nickel composite oxide is 0.05 at. % or more and 3.00 at. % or less,
wherein a water content, which is a proportion of the water in the starting material and the lithium-nickel composite oxide, is 3.0% by mass or more,
wherein a temperature of the mixing step is 30° C. or higher and 65° C. or lower, and
wherein an atmosphere of the mixing step is either a decarboxylated air or an inert gas.
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