Ion diffusion kinetics restrains the design of batteries combining both high power and high storage capacity. To bypass this limitation, structured electrodes have been demonstrated to enhance the ion diffusion, homogenize the lithium distribution, and accelerate the electrolyte wetting. Amongst the structuring technologies, ultrashort pulse laser processing may represent the key option enabling at the same time high precision, negligible material deterioration and high throughput.


Here, authors report a study on structuring of electrodes (graphite and NMC) with both holes and grooves reaching the metallic collector. Electrochemical models emphasize the importance of holes and lines dimensions on the performances of the cell. Thus, the impact of the main process parameters (fluence, repetition rate, pulses overlapping) on the topography of the laser generated surface features has been investigated jointly with the strategies required to sensibly reduce the takt-time. We demonstrate that we can control the hole and line width by adjusting the applied fluence. In addition, results show that it is possible to drill 65 µm deep and ~15 µm wide holes in nearly 100 µs resulting in up to 10,000 holes/s. Moreover, effects of a 40 MHz burst mode on the drilling time have been studied. Supported by a simple model, we show that power and burst length (number of pulses per burst) have a strong influence on the process time, which can be reduced by a factor up to 4.[AS1] Finally, preliminary tests have been carried in GHz regime to benchmark this regime with results obtained in MHz-burst regime.