Effect of Fluence and Multi-Pass on Groove Morphology and Process Efficiency of Laser Structuring for 3D Electrodes of Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) are widely used as energy storage systems. With the growing interest in electric vehicles, battery performance related to traveling distance has become more important. Therefore, there are various studies going on to achieve high-power and high-energy batteries. Laser structuring of electrodes involves a groove being produced on electrodes by a laser. This technique was used to show that battery performance can be enhanced due to improving Li-ion diffusion. However, there is a lack of studies about the morphological variation of grooves and process efficiency in laser parameters in the laser structuring of electrodes. In this study, the LiFePO4 cathode is structured by a nanosecond laser to analyze the morphological variation of grooves and process efficiency depending on laser fluence and the number of passes. First, the various morphologies of grooves are formed by a combination of fluences and the number of passes. At a fluence of 0.86 J/cm2 and three passes, the maximum aspect ratio of 1.58 is achieved and the surface area of structured electrodes is greater than that of unstructured electrodes. Secondly, three ablation phenomena observed after laser structuring are classified according to laser parameters through SEM images and EDX analysis. Finally, we analyze the amount of active material removal and process efficiency during laser structuring. In conclusion, applying low fluence and multi-pass is assumed to be advantageous for laser structuring of electrodes.