| CPC H01M 4/525 (2013.01) [C01G 53/50 (2013.01); H01M 4/505 (2013.01); H01M 10/0525 (2013.01); C01P 2002/80 (2013.01); C01P 2006/40 (2013.01); H01M 2004/028 (2013.01); H01M 2300/0017 (2013.01)] | 5 Claims |

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1. A positive electrode active material for a non-aqueous electrolyte secondary battery, comprising:
a lithium transition metal compound which contains Ni in a ratio of greater than or equal to 80 mol % and less than or equal to 94 mol % with respect to a total number of moles of metal elements other than Li, and which contains Nb in a ratio of greater than or equal to 0.1 mol % and less than or equal to 0.6 mol % with respect to the total number of moles of the metal elements other than Li, wherein
a condition of 50%≤n1/(n1+n2)<75% is satisfied in a molar amount equivalence, wherein n1 is an amount of Nb, quantitated through inductively coupled plasma atomic emission spectroscopy, in a first filtered solution obtained by dissolving a first sample solution, in which 0.2 g of the lithium transition metal compound is added to an aqueous solution of hydrochloric acid having 5 mL of pure water/5 mL of 35% hydrochloric acid, for 120 minutes under bumping, and filtering the first sample solution, and n2 is an amount of Nb, quantitated through inductively coupled plasma atomic emission spectroscopy, in a second filtered solution obtained by dissolving a second sample solution, in which a filter used for the filtration of the first sample solution is immersed in fluonitric acid having 5 mL of 46% hydrofluoric acid/5 mL of 63% nitric acid, for 180 minutes under bumping, and filtering the second sample solution.
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