| CPC H01M 4/525 (2013.01) [H01M 4/0416 (2013.01); H01M 4/505 (2013.01); H01M 4/5825 (2013.01); H01M 10/0525 (2013.01); H01M 2004/027 (2013.01); H01M 2004/028 (2013.01)] | 13 Claims |

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1. A positive active material precursor for a rechargeable lithium battery comprising:
a nickel-based composite precursor comprising a secondary particle comprising a plurality of primary particles that are aggregated together,
the nickel-based composite precursor having a central portion and a surface portion, and
the central portion of the nickel-based composite precursor comprising a phosphate between adjacent ones of the plurality of primary particles,
wherein the nickel-based composite precursor of the surface portion is represented by Chemical Formula 2,
a concentration of the phosphate in the central portion of the nickel-based composite hydroxide precursor is higher than a concentration of the phosphate in the surface portion:
NixCoyMnzM1-x-y-z(OH)2 [Chemical Formula 2]
wherein, in Chemical Formula 2,
0.7≤x≤1, 0≤y≤0.5, 0≤z≤0.5, 0.5≤x+y+z≤1, and M is at least one selected from Mn, Ni, Co, Al, Fe, V, Ti, and Cr.
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