Effects of increased pulse energy on multibeam ultrashort pulse laser structuring of battery electrodes

Laser structuring of battery active material offers possible battery performance increases combining high capacity and fast-charging capabilities. Currently, the main challenge for industrial implementation is a lack of productivity. This work explores a possible increase in productivity of electrode laser structuring with a novel ultrashort pulsed laser with an average power of 1 kW and 10 mJ pulse energy. The studies were conducted on graphite anode material in a multibeam setup with 10x10 beamlets. The investigation focused on the effects of the utilization of a high-power multibeam system for large area applications, for example heat accumulation and the corresponding effects on the material. The examined structures were holes arranged in a rectangular grid. The loss of active material due to laser ablation was kept constant at 5-6 % to ensure a comparison of electrochemical properties. The optical examination (FIB, SEM, thermographic camera, WLI) targets material integrity and geometric accuracy under variation of the laser fluence, scan strategy and structural pitch. Additionally, rate capability tests for half cells with structured graphite anode material were performed. The results demonstrate high geometric accuracy but also indicate heat accumulation from high-pulse-energy parallelized structuring, which requires more detailed investigation. However, electrochemical performance tests show no measurable degradation.