Nanosecond- and picosecond-pulsed laser cutting of lithium metal anodes with copper current collector

The cutting of lithium metal anodes is one of the key operations in the manufacturing chain for all-solid-state batteries. Due to its ductility and high surface adhesion, pure lithium is a difficult material for mechanical separation. The non-contact nature of laser-based technology, combined with its scalability for production lines, makes it a promising method for cutting lithium foil substrates. However, adequate pulse durations and cutting strategies have yet to be explored. In the scope of this work, picosecond- and nanosecond-pulsed laser systems were compared for the cutting of lithium–copper foil compounds. The influence of the layer sequence, driven by the distinct thermophysical properties of involved materials, on the process behaviour was tested by penetrating the workpiece from either the lithium or the copper side. Cause-effect relations between laser parameters and quality aspects were examined experimentally. Various cutting types were identified for the different configurations using scanning electron and laser scanning microscopy. Nanosecond-pulsed processing achieved cutting speeds of up to 2.75 and 5.00 m/s when penetrating the samples from the lithium and copper sides, respectively. Using the picosecond-pulsed laser allowed the reduction of the heat-affected zone compared to nanosecond-pulsed processing, with cutting speeds limited to 0.40 m/s, independent of the upper layer in the compound.