Abstract: In a secondary battery (1) comprising a battery case (2) for accommodating an electrode plate group (3) and an electrolyte, with one open end of the battery case (2) being sealed with an assembled sealing plate (11) that accommodates a safety mechanism (17) for exhausting pressure in the event of pressure build-up in the battery case (2) exceeding a predetermined level, at least one part (13a) of vent holes (13a, 13b, 13c) in the assembled sealing plate (11) facing the inside of the battery case (2) is constituted of an aperture that results from formation of a turned-out portion (23), the distal end of the turned-out portion (23) being allowed to abut on an insulating plate (4a) that makes contact with one end of the electrode plate group (3) so as to restrict movement of the electrode plate group (3). This can prevent malfunctioning due to displacement of the electrode plate group (3) when an impact or vibration is applied.

Abstract: In a secondary battery (1) comprising a battery case (2) for accommodating an electrode plate group (3) and an electrolyte, with one open end of the battery case (2) being sealed with an assembled sealing plate (11) that accommodates a safety mechanism (17) for exhausting pressure in the event of pressure build-up in the battery case (2) exceeding a predetermined level, at least one part (13a) of vent holes (13a, 13b, 13c) in the assembled sealing plate (11) facing the inside of the battery case (2) is constituted of an aperture that results from formation of a turned-out portion (23), the distal end of the turned-out portion (23) being allowed to abut on an insulating plate (4a) that makes contact with one end of the electrode plate group (3) so as to restrict movement of the electrode plate group (3). This can prevent malfunctioning due to displacement of the electrode plate group (3) when an impact or vibration is applied.

Abstract: 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.

Abstract: 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.