| Author: | Zhang, Songling |
| Title: | High speed and high quality laser cutting of electrodes in mass production environment |
| Advisors: | Man, H. C. (ISE) |
| Degree: | Eng.D. |
| Year: | 2020 |
| Subject: | Lasers -- Industrial applications Laser beam cutting Lithium ion batteries Hong Kong Polytechnic University -- Dissertations |
| Department: | Faculty of Engineering Department of Industrial and Systems Engineering |
| Pages: | xix, 174 pages : color illustrations |
| Language: | English |
| Abstract: | Traditional Li-ion battery electrodes die cutting can easily lead to the burring, cracking, fragmentation, deformation and efficiency problems, which seriously affect the production of and performance of batteries. This project presents an efficient and high-quality laser cutting method, establishes a process model of laser cutting with high efficiency and quality, as well as particle analysis, reduce and control method, and validates the models and technology through simulation and experiment. Specific researches are as follow: (1) Study the interaction between laser and electrodes materials, establish heat transfer model, state change effect and energy conversion effect, study the output mode of laser beam, establish the theoretical model of laser tab cutting, deeply study the methods of melting cutting and ultra-fast laser cutting, and study the influence of the cutting power, cutting speed, beam quality and focus position of on cutting quality, build the process correlation model of laser cutting parameters, math model for tab cutting, and provide guidance for mass production, to achieve high speed and quality. (2) Study the principle of dust particles generated by laser cutting, calculating the particle size, composition and amount, analyze the reason of slash, and splash speed, metal melting and cooling time, trajectory, direction of particles, and observe the result through experiment. Method for reduce and remove particles are established. Fluent is used to do the CDF simulation dust removing system. Reasonable model and simulation results are obtained, shows that the simulation with Fluent is consistent with the theoretical analysis. Experiment result shows the design of dust remove system is effective and simulation conform with the actual system. (3) Short pulse picosecond laser is studied and experiments are conducted to have a preliminary understanding the characteristics of picosecond laser cutting, and comparison the cutting quality with nanosecond laser. (4) Finally, based on the process and mathematical model established and particle analysis here, large quantity batteries are tested to verify the effectiveness of process model and particle analysis. The impedance, capacity, cycle performance, anatomy analysis under charge retention and open charge voltage drop performance are tested with batteries made using laser cut and die cut electrodes. The results show that the process model, and particle analysis and control method presented in this paper are very effective, which can bring high speed and high quality laser cutting, and great advantages over die cutting process. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 5103.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 15.8 MB | Adobe PDF | View/Open |
Copyright Undertaking
As a bona fide Library user, I declare that:
- I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
- I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
- I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.
Please use this identifier to cite or link to this item:
https://theses.lib.polyu.edu.hk/handle/200/10675