Nonaqueous electrolyte secondary battery

A nonaqueous electrolyte secondary battery comprising:

• an electrode assembly having a high-density positive electrode in which a positive electrode active material layer is formed on at least one surface of a positive electrode current collector, a high-density negative electrode in which a negative electrode active material layer is formed on at least one surface of a negative electrode current collector, and a separator interposed between the positive and negative electrodes, and having a structure in which the electrode assembly is impregnated with a nonaqueous electrolyte,
• wherein a plurality of grooves are formed in a formation surface of the positive electrode active material layer of the positive electrode, such that end portions of the grooves open at edges of the positive electrode active material layer, and
• the grooves are formed at a frequency of 1 to 10 grooves per mm as a length of the positive electrode active material layer, and a sectional area of the grooves, as viewed in a length direction of the grooves, account for a ratio of 1 to 20% of a sectional area of the positive electrode active material layer as viewed in the length direction of the grooves.