NONAQUEOUS-ELECTROLYTE SECONDARY BATTERY

摘要

According to one embodiment, there is provided a nonaqueous electrolyte secondary battery comprising a positive electrode and a negative electrode. The positive electrode comprises a positive electrode current collector having a first surface and a positive electrode active material layer. The negative electrode comprises a negative electrode current collector having a second surface opposed to the first surface and a first negative electrode active material layer provided on a part of the second surface. The negative electrode current collector comprises a coated portion on which the first negative electrode active material layer is provided and a noncoated portion which is adjacent to the coated portion in a direction parallel to the second surface, in which the first negative electrode active material layer is not present. The noncoated portion is adjacent to at least one edge of the negative electrode current collector and extends along the at least one edge. A length from a boundary between the coated portion and the noncoated portion to the at least one edge of the negative electrode current collector is within a range of 5 mm to 20 mm. A density of the first negative electrode active material layer is within a range of 2.1 g/cc to 2.4 g/cc. A ratio W1/W2 of a mass of the coated portion per unit area (W1) to a mass of the noncoated portion per unit area (W2) is from 0.997 to 1.