Method for welding electrode leads of secondary battery module and compact secondary battery module using the same

A compact secondary battery module, comprising:

• a plurality of cartridges configured to accommodate cells, respectively, the plurality of cartridges stacked in a first direction;
• a first battery cell accommodated in a first cartridge of the plurality of cartridges, the first battery cell having a first lead extending from the first cartridge;
• a second battery cell accommodated in a second cartridge of the plurality of cartridges, the second battery cell having a second lead extending from the second cartridge;
• and
• a sensing housing arranged at a side of a cartridge assembly in which the cartridges are stacked, the sensing housing having a plurality of bus bars,
• wherein corresponding electrode leads of adjacent cells are arranged to be coplanar in a first plane and one of the plurality of bus bars in a second plane overlaps the first lead and second lead and then is welded to the first lead and second lead at two welding points, the second plane being parallel to the first plane, and
• wherein the corresponding electrode leads of adjacent cells are spaced from one another in the first direction.