CPC H01M 10/052 (2013.01) [H01M 10/0587 (2013.01); H01M 50/414 (2021.01); H01M 50/417 (2021.01); H01M 50/423 (2021.01); H01M 50/426 (2021.01); H01M 50/463 (2021.01); H01M 50/489 (2021.01); H01M 50/491 (2021.01)] | 4 Claims |
1. A nonaqueous electrolyte secondary battery comprising:
a wound electrode body which is obtained by winding a positive electrode and a negative electrode through a separator and which is formed into a flat shape having a flat part and a pair of curved parts;
a nonaqueous electrolyte; and
a battery case which houses the electrode body and the nonaqueous electrolyte,
wherein the separator contains a first region located in the flat part of the electrode body and second regions located in the pair of curved parts, a ratio (B/A) of an air permeability (B) in each of the second regions to an air permeability (A) in the first region being 0.52 or more and 0.83 or less; and
in a section passing through the center in an axial direction of the electrode body and being perpendicular to the axial direction, a ratio (SB/SA) of a sectional area (SB) of the pair of curved parts to a sectional area (SA) of the flat part is 0.281 or more and 0.318 or less, and
a ratio (K/W) of a length (K) of a positive electrode mixture layer along the axial direction of the electrode body to a length (W) in the direction perpendicular to the axial direction and the thickness direction of the electrode body is 1.61 or more and 1.93 or less.
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