Laser welding of busbars with beam shaping

A method for joining busbars, the method comprising:

• emitting, using a laser source, a raw laser beam,
• reshaping the raw laser beam to obtain a reshaped laser beam, wherein the reshaped laser beam comprises a core focus portion and at least one ring focus portion, the core focus portion and the at least one ring focus portion being coaxial with respect to one another and the ring focus portion surrounding the core focus portion,
• directing the reshaped laser beam to a plurality of busbars to weld the plurality of busbars to one another along at least one weld seam,
• at a beginning of welding of a start section of the weld seam, initially decreasing an instantaneous average laser power of the reshaped laser beam and then increasing the instantaneous average laser power, and
• during welding of an end section of the weld seam, decreasing the instantaneous average laser power.