A non-aqueous electrolyte secondary battery includes a positive electrode (11), a negative electrode (12), a separator (13), and a non-aqueous electrolyte solution. The positive electrode (11) contains a positive electrode active material (1), a conductive agent, and a binder. In the positive electrode, the positive electrode active material is not entirely coated with the conductive agent, and the separator satisfies the condition x·y≦1500 (μm·%), where x is the thickness (μm) and y is the porosity (%) of the separator. The non-aqueous electrolyte solution contains LiBF4. The positive electrode is charged to 4.40 V or higher versus a lithium reference electrode potential.