A battery module for energy storage is provided, comprising at least one battery unit, including: first and second battery cells comprising first and second electrode tabs as well as third and fourth electrode tabs respectively; first and second connection structures comprising first support/connection portions as well as second support/connection portions respectively, regarding material, first and second support portions being different from materials of first and second connection portions, regarding polarity, the first and second electrode tabs being the same as the third and fourth electrode tabs, both first and fourth electrode tabs being lap-jointed with the first support portion and connected by welding via the first connection portion; and the second electrode tab is lap-jointed with the second support portion and connected by welding with the second connection portion, so as to achieve the welding between electrode tabs with different polarities and expedite the manufacturing schedule for battery module.