Secondary battery and manufacturing method thereof
View Patent ↗The present disclosure discloses a secondary battery and a manufacturing method thereof. According to the present disclosure, the influence of heat generated at a welding spot between an electrode tab and an electrode lead on the performance of a secondary battery may be minimized. Accordingly, in the design of a large capacity secondary battery, the battery performance may be close to an ideal condition.
1. A secondary battery comprising:
a cell assembly having a stack of at least two unit cells, each unit cell including a cathode plate, a separator, and an anode plate;
a plurality of electrode tabs including a cathode tab protruding from the cathode plate and an anode tab protruding from the anode plate for each unit cell;
a plurality of electrode leads including a cathode lead electrically connected to a plurality of cathode tabs and an anode lead electrically connected to a plurality of anode tabs;
a welding part which mechanically connects a selected electrode tab to a selected electrode lead; and
a case which seals the cell assembly such that a part of the selected electrode lead is exposed to an outside of the case,
wherein the welding part is formed near the cell assembly within a ½ area closer to the cell assembly along a lengthwise direction of the selected electrode lead on a surface where the selected electrode tab is each in contact with the selected electrode lead.
2. The secondary battery according to claim 1 , wherein the welding part is formed within a ⅓ area closer to the cell assembly along a lengthwise direction of the selected electrode lead on a surface where the selected electrode tab is each in contact with the selected electrode lead.
3. The secondary battery according to claim 1 , wherein the welding part is formed by resistance welding, ultrasonic welding, laser welding, or a conductive adhesive.
4. The secondary battery according to claim 3 , wherein the welding part is formed in a shape of a point or a line.
5. The secondary battery according to claim 3 , wherein the welding part is formed in multiple numbers.
6. A method for manufacturing a secondary battery, comprising:
(a) preparing a cell assembly in which at least two unit cells including a cathode plate, a separator, an anode plate, and a plurality of electrode tabs including a plurality of cathode tabs and a plurality of anode tabs;
(b) providing a plurality of electrode leads including a cathode lead and an anode lead;
(c) forming a welding part at a region on a surface where a selected tab is in contact with a selected lead, to mechanically connect the selected tab to the selected lead, the region being disposed within a ½ area closer to the cell assembly along a lengthwise direction of the selected lead on a surface where the selected tab is in contact with the selected lead; and
(d) loading the cell assembly in between the case such that parts of the cathode lead and the anode lead are exposed to outside, and sealing the case.
7. The method for manufacturing a secondary battery according to claim 6 , wherein the step (c) comprises forming the welding part within a ⅓ area closer to the cell assembly along a lengthwise direction of the selected lead on the surface where the selected tab is each in contact with the selected lead.
8. The method for manufacturing a secondary battery according to claim 6 , wherein the step (c) comprises forming the welding part by resistance welding, ultrasonic welding, laser welding, or a conductive adhesive.
9. The method for manufacturing a secondary battery according to claim 8 , wherein the step (c) comprises forming the welding part in a shape of a point or a line.
10. The method for manufacturing a secondary battery according to claim 8 , wherein the step (c) comprises forming a plurality of welding parts.