# Investigation of Laser Cutting Width of LiCoO\({}_{2}\) Coated Aluminum for Lithium-Ion Batteries
## 1 Introduction  
Lithium-ion batteries, which are secondary batteries, are used for portable electronic devices, Electric Vehicles (EV), and Plug-in Hybrid Electric Vehicles (PHEV), because they are lighter and have a higher energy density, power density, and energy-to-weight ratio than lead-acid batteries and nickel-cadmium batteries [1; 2]. Due to these advantages, material research on lithium-ion batteries has been actively done to improve battery performances [3]. However, the performance of the lithium-ion battery can be also affected by the manufacturing processes. Lithium-ion batteries' cell design is not standardized because their shapes and capacities are different according to their applications and requirements. Therefore, conventional cutting technology such as die cutting and rotary knife slitting may be inefficient since tools need to be re-designed so that an additional manufacturing costis required whenever the cell design changes. Furthermore, the conventional cutting technology may result in process instability and poor cut quality due to the tool wear. Therefore, this poor cut quality leads to short circuits and local heat concentration [2]. This process instability and inefficiency may be solved by laser processing since it has many advantages, such as a clean cutting edge, less deformation, applicability to almost all materials, possibility of precision processing, and an easy transition of cutting path [4; 5; 6; 7; 8; 9].  
[PERSON] et al. [2; 10; 11] proposed a mathematical model to understand multi-physical phenomena during the laser cutting of electrodes using a single mode fiber laser. This mathematical model is used to investigate the laser cutting on current collectors such as copper and aluminum [2], and composite laser cutting such as anode and cathode [10; 11]. Furthermore, laser parameters are experimentally optimized for high speed remote laser cutting [12]. [PERSON] et al. [13] characterized the process efficiency and quality for laser cutting of lithium iron phosphate battery electrodes. They found that the cutting efficiency increases with shorter pulses, higher velocity, and shorter wavelength. Furthermore, in his recent publication, high speed laser cutting of Li-ion battery electrodes had been investigated to provide guidelines for the processing parameters to achieve optimum process efficiency and visible cut quality with a high power nanosecond pulsed laser [14]. [PERSON] [15] proposed an analytical model to understand the laser ablation mechanism of lithium-ion battery coating. This model was verified by a time resolved shadowgraph imaging and experiments. Among this research, no clear definition of cutting widths has been presented and there is lack of knowledge to understand the effect of laser parameters on cutting widths. Therefore, this research examines the surface morphology of cathode cut by a laser and defines meaningful cutting widths. The relationship between laser parameters and cutting widths are studied. Furthermore, the material removal rate of active electrode material and the clearance width of cathodes are calculated by the defined widths. In addition, five types of physical characteristics with a cross-sectional view are defined and discussed with volume energy and cut surface images. Moreover, the effect of material properties on heat transfer using a one dimensional transient semi-infinite conduction model is presented. This paper is organized as follows. First, an experimental setup, procedures, and material information are described. Second, cutting widths are defined, as well as cut surface is investigated and discussed. Finally, the conclusions drawn from this study are summarized.