| CPC H01M 4/525 (2013.01) [H01M 2004/027 (2013.01); H01M 2004/028 (2013.01)] | 3 Claims |

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1. A non-aqueous electrolyte secondary battery comprising:
a positive electrode including a positive electrode active material;
a negative electrode including a negative electrode active material; and
a non-aqueous electrolyte, wherein
the positive electrode active material includes a lithium transition metal oxide having a layered structure including a Li layer in which Li reversibly moves in and out, and including at least Ni, Ca and Al;
in the lithium transition metal oxide,
a content of Ni is 80 mol % or more and 95 mol % or less relative to a total amount of metal elements excluding Li;
a content of Ca is more than 0 mol % and 3 mol % or less relative to the total amount of metal elements excluding Li;
a content of Al is more than 0 mol % and 8 mol % or less relative to the total amount of metal elements excluding Li;
a proportion of metal elements excluding Li present in the Li layer is 0.6 mol % or more and 2.0 mol % or less with respect to a total number of moles of metal elements excluding Li included in the lithium transition metal oxide;
the negative electrode active material comprises a film including Ca on a surface thereof; and
a proportion of Ca in the film is 15 ppm by mass or more and less than 80 ppm by mass relative to a total mass of the positive electrode active material.
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