US Patent 7438994 Non-aqueous electrolyte secondary battery

A non-aqueous electrolyte secondary battery has a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution. The positive electrode has a theoretical capacity per unit area from 3.0 to 4.5 mAh/cm2. The non-aqueous electrolyte solution contains ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) as solvents, and LiPF6 as an electrolyte, with volume ratios from 10 to 20% for EC, 10 to 20% for EMC, and 60 to 80% for DMC relative to all the solvents in the electrolyte solution. The concentration of the LiPF6 is from 1.30 to 1.50 mol/L.