| abstract |
The nonaqueous electrolyte secondary battery includes a positive electrode 13, a negative electrode 17, a separator 15 provided between the positive electrode and the negative electrode, and a nonaqueous electrolyte held by the separator. The separator has a first separator layer 15A that faces the positive electrode and a second separator layer 15B that faces the negative electrode. The 1st separator layer 15A and the 2nd separator layer 15B have a shutdown function, respectively, The thickness of the 1st separator layer 15A and the thickness of the 2nd separator layer 15B are the same, and the 1st separator layer When the porosity (%) formed in (15A) is represented by (alpha), and the porosity (%) formed in the 2nd separator layer 15B is represented by (beta), the following is satisfied. α <90 |