Non-Aqueous Electrolyte Secondary Battery

A non-aqueous electrolyte secondary battery which has a ratio value of a battery volume, defined as a product of a projected area of the battery including a battery outer casing body and a thickness of the battery, to a rated capacity of 10 cm3/Ah or less and a rated capacity of 3 Ah or more, the battery comprising:

• a power generating element including
• a positive electrode comprising a positive electrode active material layer containing a positive electrode active material formed on a surface of a positive electrode current collector,
• a negative electrode comprising a negative electrode active material layer containing a negative electrode active material formed on a surface of a negative electrode current collector, and
• a separator, wherein
• the negative electrode active material layer comprises a negative electrode active material represented by the following Formula (1):
• α(Si material)+β(carbon material) (1)
• wherein the Si material is a Si-containing alloy;
• the carbon material is one or two or more kinds selected from the group consisting of graphite, non-graphitizable carbon, and amorphous carbon;
• α and β represent % by mass of each component in the negative electrode active material layer;
• and 80≤α+β≤98, 0.1≤α≤40, and 58≤β≤97.9 are satisfied), and
• when area proportions (%) of the Si material and the carbon material in an area of a field of view of each image of cross-sections of the negative electrode active material layer in a case where a plurality of arbitrary places is selected in a plane of the negative electrode active material layer are designated as S (%) and (100−S) (%), respectively, a difference between the maximum value and the minimum value of S is within 5%.