| 摘要 |
PURPOSE: A secondary battery is provided to increase a welding strength of a negative electrode to be the same as welding strength of a positive electrode by forming high welding point density on a welding adhesive side of a negative electrode, and to solve contact resistance non-uniformity phenomenon between both electrodes. CONSTITUTION: A secondary battery comprises: an electrode assembly in which a positive electrode tab(310) with a positive electrode plate, a negative electrode plate with a negative electrode tab(320), and a separator are alternately laminated; a pouch external material accommodating the electrode assembly; a positive electrode lead(330) electrically connected to the positive electrode tab through a welding; and a negative electrode lead(340) electrically connected to the negative electrode tab through a welding. The diameter of a welding point(361) formed on a welding adhesive side(380) of the negative electrode lead and the negative electrode tab is longer than the diameter of a welding point(351) formed on the welding adhesive side of the positive electrode lead and the positive electrode tab.
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