| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery that is still safer.SOLUTION: A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, a separator provided between the positive electrode and the negative electrode, and nonaqueous electrolyte held by at least the separator. The separator includes at least a first separator layer which is opposed to the positive electrode and made of polypropylene, a second separator layer which is opposed to the negative electrode and made of polypropylene, and a third separator layer which is provided between the first separator layer and the second separator layer and made of polyethylene. When the porosity (%) of the first separator layer is represented by α, the porosity (%) of the second separator layer is represented by β, the porosity (%) of the third separator layer is represented by γ, and the specific surface area (m/g) of the positive electrode active material contained in the positive electrode is represented by δ, the following formulas 1 to 4 are satisfied: 20%<α≤25% (formula 1), 80%≤β<85% (formula 2), 15%<γ≤20% (formula 3), and δ≥3.0 m/g (formula 4).SELECTED DRAWING: None |
