High quality remote laser cutting of polymer lithium-ion battery separator using a NIR picosecond-pulsed laser

Due to the increasing demand for electrification in general and battery manufacturing in particular, there is a need to use digital tools wisely. Laser is a digital tool that could process materials with high precision and quality. The polymer separator is one of the basic components of lithium-ion battery, which has the significant effect on the performance of lithium-ion battery. The remote laser cutting of the 25 µm-thick lithium-ion battery separator was experimentally investigated using nanosecond and picosecond near-infrared laser systems. The ns-pulsed laser was found to be sensitive to the material directionality and it could not achieve melt free cuts at processing conditions suitable for the industrial production. The ps-pulsed laser produced clean cut kerfs at high productivity. In terms of cutting productivity, the cutting speed of the ultrashort pulse laser system is approximately 700 times that of the short pulse laser system. To estimate the change in the material’s optical properties, the fluence efficiency model was employed. It was found that the apparent optical absorptivity of the material changes from 0.4 cm⁻¹ to 1400 cm⁻¹ when the pulse duration is changed from the nanosecond to the picosecond regime for the same wavelength.