Modeling of High Speed Remote Laser Cutting of Electrodes for Lithium-ion Batteries.

High Speed Remote Laser Cutting of Electrodes for Lithium-ion Batteries;Mechanical Engineering;Engineering;Mechanical Engineering

Lee, DongkyoungPipe, Kevin Patrick ;

University of Michigan

关键词: High Speed Remote Laser Cutting of Electrodes for Lithium-ion Batteries;    Mechanical Engineering;    Engineering;    Mechanical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/96088/keyenlee_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This research investigates the underlying physics of the laser cutting of electrodes for lithium-ion batteries and validates important findings experimentally. The mathematical model considers heat transfer, mass transfer, fluid flow, melting, solidification, evaporation, kinetic Knudsen layers, multiple reflections, free surface evolution, and composite materials.First, the developed model is applied to investigate effects of laser beam modes on the laser-material interaction. Cylindrical TEM00, TEM01*, TEM22, and Top-hat laser beam are selected. Overall characteristics such as, response time, depth, width, and absorptivity of the proposed cases are investigated. The criteria of keyhole collapse are quantitatively obtained. The result indicates that the TEM00 and Top-hat laser beam cases are more efficient for the laser cutting process.Second, the model is applied to the laser cutting of current collectors. Laser parameter thresholds for cutting are obtained. Moreover, L/V interface geometry, melt pool flow, and temperature distribution are examined. The analysis shows interaction characteristics of current collectors with the laser. Furthermore, results present the formation of crests and two consecutive deep penetration holes as well as explain possibilities of forming a spatter, recast layer, and a neck.Third, the model is applied to the laser cutting of electrodes. Interesting results near the material interface between current collectors and active electrode materials are observed. For the anode, the L/V interface in the graphite region shows a smooth and clean surface, and a two-level surface is observed near the material interface. For the cathode, the deep penetration hole shows an uneven surface, crests, and a protrusion in the LiCoO2 region. The narrower deep penetration hole forms near the material interface.Finally, experimental results are presented. The kerf widths are compared near thresholds of the laser cutting of current collectors. The kerf width of electrodes and composition change along the cut surface of electrodes are validated. The theoretical prediction shows a reasonable agreement with experimental observations. Moreover, the optimum range of laser parameters providing both high speed and high quality cutting are obtained.The proposed model can be utilized to predict and prevent defects, thermal stress, significant heat generation, and eventually catastrophic failures of the entire module.