Method of Manufacturing Battery Module and Battery Module Manufactured Thereby
Provided are a battery module housing welding method capable of solving a problem that a battery cell accommodated therein is damaged due to heat that occurs during welding, and a battery module manufactured thereby, and according to the battery module housing welding method of the present invention, a gap portion formed during assembling of a battery module housing is welded by lasers with different powers and sizes a plurality of times, thereby preventing damage to a battery cell due to high temperatures during welding of the housing.
1 . A method of manufacturing a battery module by welding a battery module housing including a lower housing accommodating a battery stack cell formed by stacking a plurality of pouch cells with a protruding electrode tab, the lower housing accommodating the battery stack cell to face a lower portion and both side surfaces of the battery stack cell, a front cover and a rear cover coupled to the front and rear of the lower housing, and a cover plate disposed at an upper portion of the battery stack cell and coupled to both edges of the lower housing, the method comprising:
a stack cell inserting operation of inserting a battery stack cell into the lower housing;
a module case assembling operation of assembling the front cover, the rear cover, and the cover plate to the stack cell-inserted lower housing;
a first welding operation of welding, by a laser, a gap portion formed between any one of the cover plate, the front cover, and the rear cover and an assembly surface of the lower housing in the module case assembling operation; and
a second welding operation of welding the gap portion by a laser different from the laser used in the first welding operation after the first welding operation.
2 . The method of claim 1 , wherein, in the second welding operation, the gap portion is welded with a power lower than a laser power in the first welding operation.
3 . The method of claim 2 , wherein the laser power in the second welding operation is 0.25 times to 0.4 times the laser power in the first welding operation.
4 . The method of claim 2 , wherein a size of a laser spot in the first welding operation is smaller than a size of a laser spot in the second welding operation.
5 . The method of claim 2 , wherein the welding in the first welding operation and the second welding operation is wobble welding.
6 . The method of claim 5 , wherein the wobble welding laser overlap rate in the first welding operation is lower than a laser overlap rate in the second welding operation.
7 . A battery module manufactured by the method of manufacturing a battery module of claim 1 , the battery module comprising:
a battery stack cell formed by stacking a plurality of pouch cells with a protruding electrode tab;
a lower housing accommodating the battery stack cell to face a lower portion and both side surfaces of the battery stack cell;
a front cover and a rear cover disposed to face the electrode tap of the pouch cell and coupled to the lower housing; and
a cover plate disposed at an upper portion of the battery stack cell and coupled to both edges of the lower housing,
wherein a gap portion is formed on an assembled surface between the lower housing and the cover plate, the front cover, and the rear cover, and a first welded portion formed by the first welding operation and a second welded portion formed by the second welding operation.