GHz and MHz Burst enhanced femtosecond laser structuring of electrodes for improved Li-Ion battery performances

We report on a comparative study of MHz and GHz bursts for femtosecond laser structuring of electrodes (graphite-silicon composite and high nickel content NMC coatings). Influences of average power, burst length and intra repetition rate on the matter removal rate were investigated for drilling and grooving with both holes and grooves reaching the metallic collector. Removal rates and resulting machining qualities, investigated by SEM, were compared between single pulse (SP) and bursts (clocked at 40 MHz and 1.28 GHz). Fastest processing conditions for which SP and burst machining qualities are comparable were identified by SEM. In accordance with an ablation model, results indicate that removal rates depend strongly on the burst duration and slightly on the intra-repetition rate. MHz and GHz burst modes can decrease the processing time by a factor up to respectively 4 and 5.