Interconnector for batteries

A battery module is provided comprising a plurality of rechargeable batteries (110), and a connecting member (160, 170, 260) for connecting a first electrode terminal (130) of a first rechargeable battery comprising a first material with a second electrode terminal (140) of a second rechargeable battery comprising a second material. Welding portions (150, 175, 250) are provided connecting the connecting member (150, 175, 250) to the first terminal and the second terminal (130, 140), wherein at least the welding portions (150, 175, 250) to one of the first or second electrode terminal (130, 140) comprises a nugget zone (152, 252), The nugget zone comprises a mixture of the materials of the connecting member (160, 170, 260) and the respective first or second electrode terminal (130, 140).