| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion battery with high vibration proof and high safety. SOLUTION: The cylindrical lithium ion battery 20 is provided with a wound-up group W which has a positive electrode with a positive electrode active material layer W2 formed on a positive electrode collector W1 and a negative electrode with a negative electrode active material layer W4 formed on a negative electrode collector W3 wound up spirally in cross section through a separator W5. On a top lid, a safety valve 3 splitting open according to rise of inner pressure of the battery is arranged, and on a bottom is also arranged an open valve. When the diameter of a battery can 16 is D (unit in mm), and the length, L (unit in mm), the ratio D/L of the diameter D to the length L is set at 0.4 to 0.6. The electrode wound-up group W is prevented from moving by being surely supported, and gas generated when overcharged is quickly released outside the battery. |
