Cutting out electrodes sheets is an important process step in the production of automotive lithium ion batteries. Laser cutting is an innovative way to singularise electrode sheets. This process combines the conventional notching of the current collector and cutting out electrode sheets as well as provides a high cutting flexibility.
However, this novel process also incorporates new challenges in view of producing high quality electrode sheets without any cutting defects in combination with high production speed.
We had been investigating this technology using cathode electrodes based on lithium-iron phosphate (LFP). Our investigations reveal that two main defects may occur when laser cutting LFP cathodes: welding beds and frayed edges of the electrodes.
The figures in the appendix show that the use of inappropriate process parameters massively impacts the electrode quality and hence the quality of the finally assembled cell in a significant way. These defect patterns had been systematically investigated by varying the laser parameters such as cutting velocity, frequency, maximum and average power.
The results of the comprehensive parameter study unfold that the two defects mentioned above can be successfully eliminated, if laser parameters are optimized in regards of the used electrodes and the chemistry used in the electrodes.