High Speed Pulsed Laser Cutting Of Anode Material For A Li-Ion Battery In Burst Mode

Characterized by high energy density [1], high voltage, low self-discharge rate [2], no memory effect [3], and long cycle life [4], etc., Li-ion batteries are ideal power sources for portable electronic devices and emerging unmanned aerial vehicle (UAV) products and also preferred power sources for electric and hybrid vehicles. A Li-ion battery is composed of a copper anode coated with graphite active material, an aluminum cathode coated with lithium iron phosphate (LiFePO4), separator film and electrolyte, and its production is completed through cutting, stacking, electrolyte filling, and packaging [5,6]. The current large-scale and wide applications of Li-ion batteries require more flexible production means to adapt to varied sizes of Li-ion battery products, and laser cutting provides a very good solution. In order to overcome such problems in mechanical blanking as restriction to product compatibility by die, long time for model changeover, and stress-caused stretching of, curling of and active material coming-off from electrode [7], the cutting process for Li-ion battery begins to turn to laser cutting as a newThe bursts of picosecond laser pulses have nanosecond-level short interval delay. These bursts contain a variable number of sub-pulses, which are used for laser cutting of copper current collector and graphite anode material for Li-ion battery anode. The influences of 2-10 sub-pulses on kerf edges were studied and were compared with that of a single pulse. The shapes of anode edge cut under different conditions, obtained using scanning electron microscopy (SEM), revealed that using burst mode would yield a smaller heat-affected zone (HAZ) of the copper current collector and smaller delamination width of graphite anode material. The capability of laser cutting of anode was characterized with maximum single-time cutting speed. Results showed that the cutting efficiency was raised evidently with the increase in the number of pulses in a burst, and the maximum cutting speeds for the copper current collector and graphite anode material could reach 3,800 mm/s and 500 mm/s respectively.