| CPC H01M 4/505 (2013.01) [H01M 4/525 (2013.01); H01M 10/052 (2013.01); H01M 10/0568 (2013.01); H01M 2004/021 (2013.01); H01M 2004/028 (2013.01); H01M 2300/0037 (2013.01)] | 10 Claims |

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1. A nonaqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte,
wherein the nonaqueous electrolyte secondary battery has undergone an initial charge-discharge,
a maximum potential of the positive electrode in the initial charge-discharge is less than 4.5 V (vs. Li/Li+),
the positive electrode contains, as a positive active material, a lithium transition metal composite oxide of Li(1+α)(NixCoyMnz)(1−α)O2 where x+y+z=1 and 0<α, the lithium transition metal composite oxide having:
an α-NaFeO2 type crystal structure,
a molar ratio of Li to Me, Li/Me of more than 1, Me representing transition metal elements including Ni, Mn, and Co,
a molar ratio of Mn to Me, Mn/Me of 0.40 or more and 0.65 or less, and
a diffraction peak observed in a range of 20 to 22° in an X-ray diffraction diagram obtained using a CuKα ray, and
the nonaqueous electrolyte contains, as an electrolyte salt, LiPF6 and LiN(FSO2)2.
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