Laser cutting and welding of lithium-ion batteries for e-mobility applications

The rapid expansion of electric mobility requires lithium-ion batteries with higher performance, improved safety, and lower cost, placing increasing demands on manufacturing technologies. In this context, electrode cutting and electrical interconnection by welding are critical process steps that strongly affect cell reliability, efficiency, and sustainability. This thesis investigates laser-based cutting and welding technologies for lithium-ion battery production, with particular focus on copper and aluminum current collectors and tab-to-busbar joints. The work combines systematic experimental investigations with numerical modeling to analyze the influence of laser parameters, including continuous-wave, pulsed, and ultrafast regimes, on cut-edge quality, thermal defect formation, and process efficiency. A computational model is developed to describe melt-pool dynamics and thermal effects during high-speed cutting and is validated against experimental data obtained over a wide range of scanning speeds. In parallel, advanced in-process monitoring strategies for laser welding are studied using photodiodes, high-speed imaging, and optical microphones in order to correlate sensor signals with weld quality and process stability. The results demonstrate that appropriate selection and optimization of laser sources and process parameters enable high-quality, high-throughput cutting and reliable welding suitable for industrial battery manufacturing. Overall, the thesis provides quantitative insight and practical tools to enhance the robustness, productivity, and sustainability of laser-based processes in lithium-ion battery production.