Contacting of 18650 lithium-ion batteries and copper bus bars using pulsed green laser radiation

Lithium-ion cell based battery storages are indispensable in many fields of application such as electromobility and stationary energy storage devices. Cylindrical 18650 cells are regularly utilized and connected by cell connectors made of nickel plated steel. Since this setup suffers from high electrical losses and a poor heat removal during operation, copper connectors are demanded more often. For joining the cells and the connectors, laser beam welding offers great potential due to its low energy input and high flexibility. However, challenges arise, as copper materials show a strong reflectivity for infrared wavelengths. Experimental investigations for the contacting of 18650 cells and copper connectors using a spike pulse welding strategy combined with green laser radiation are presented within this study.