Views: 3 Author: Site Editor Publish Time: 2024-08-29 Origin: Site
Laser cleaning technology and applications
in the field of finishing technology
With the rapid development of new energy vehicles around the world, the demand for lithium batteries, one of the core components, has also increased dramatically.
Therefore, the lithium battery manufacturing process involved in the finishing technology also usher in new tasks and challenges.
The preparation process of lithium batteries is divided into the front-end process (electrode manufacturing), the middle-end process (cell synthesis), and the back-end process (formation and packaging).
Among them, the purpose of the front-end process is to process the raw materials into pole pieces, and the core process is coating.
The purpose of the middle-end process is to process the pole pieces into unactivated cells.
The back-end process is testing and packaging, and the core process is formation and capacity separation.
1. Electrode sheet production
2. Cell synthesis
3. Forming packaging
Laser cleaning technology is one of the important finishing technologies in the preparation process of lithium batteries.
This article will analyze how to promote the development of new energy automobile industry from the perspective of laser cleaning technology, application and equipment.
Laser cleaning process
Laser cleaning, known as "the most promising green cleaning technology in the 21st century", mainly has two modes: handheld and automatic.
Compared with traditional cleaning methods, laser cleaning has a wider range of applications and has significant advantages such as green environmental protection, low cost, high efficiency, high precision and non-contact processing.
In recent years, it has been widely used in industrial production, such as automobile manufacturing, aerospace, precision electronics, medical equipment, ships and other fields.
Laser cleaning VS Chemical cleaning VS Mechanical polishing
Laser cleaning application
Laser cleaning before electrode coating
The positive and negative electrodes of lithium batteries are made by coating electrode materials on aluminum foil and copper foil. The common positive electrode collector is aluminum foil, and the negative electrode collector is copper foil. The main core process of this process is coating. In order to avoid impurities, dust and other media causing micro short circuits inside the battery, the copper and aluminum foil need to be cleaned before coating to ensure the stability of the subsequent current collector inside the battery. The purity of the copper and aluminum foil should reach more than 98%, with high cleanliness and a surface without an oxide layer.
Traditional wet ethanol cleaning can damage other parts of lithium batteries, causing the mechanical properties of aluminum foil to decline and causing "hydrogen embrittlement". Although ultrasonic cleaning technology is better than traditional wet ethanol cleaning, it still has some defects. For example, when metal foil is under the cavitation effect of ultrasonic cleaning, it is easy to corrode the aluminum foil and produce shrinkage holes. In addition, the foil used for lithium battery pole pieces is generally single zero foil with a thickness of 10μm. With the influence of cleaning time and power, the small holes will become larger and larger.
Laser cleaning is a dry, consumable-free cleaning method that can achieve near-zero defects in terms of surface cleanliness and hydrophobicity of aluminum foil. At the same time, it can also improve the efficiency of the cleaning process and save cleaning resources. Most importantly, it can establish real-time monitoring of cleaning process data and quantitative determination of cleaning results, to maximize the effect of electrode sizing and coating, and improve the consistency of electrode batch production.
Laser cleaning of battery cell tabs before welding
The tabs are metal strips that lead out the positive and negative electrodes in the battery, and serve as contact points during charging and discharging. Before welding, each welding part needs to be surface treated to remove contaminants at the weld joint. A clean and uniform surface is a prerequisite for welding and bonding, otherwise it may lead to problems such as poor welding, cracks and pores at the weld, thus affecting the reliability and durability of the electrical connection.
Manual cleaning is inefficient and costly, while plasma cleaning requires the use of process gas as consumables. At the same time, gas ionization will make the positive and negative poles of the battery easy to conduct. Therefore, when applying, it is often necessary to flip the battery cell several times to separate the positive and negative poles for cleaning, and the efficiency will be greatly reduced.
Laser cleaning can effectively remove dirt, dust, etc. on the end face of the battery pole without using any consumables, such as solid, liquid, and gas. It can also greatly improve the production cycle and reduce manufacturing costs. Before welding, pulsed laser direct radiation decontamination is used to increase the surface temperature and cause thermal expansion, so that the pollutant or the substrate vibrates, so that the pollutant overcomes the surface adsorption force and leaves the substrate surface, achieving the purpose of removing stains on the surface of the object.
Laser cleaning of external adhesive during battery assembly
To prevent safety accidents of lithium batteries, it is usually necessary to insulate the battery cells with external adhesive. Before this, the insulating plate and end plate should be cleaned to clean the dirt on the surface of the battery cell and roughen the surface of the battery cell, so as to improve the adhesion of the adhesive or glue coating, which can effectively avoid the occurrence of safety problems such as short circuit and scratches.
Manual cleaning technology only performs simple wrapping operations, which is inefficient and costly. Before coating, the battery shell is not effectively and comprehensively cleaned, and the effect after coating is not accurately tested. If CCD inspection is performed on the outer film of the battery cell that has not been thoroughly cleaned, wrinkles, bubbles, scratches and other undesirable conditions will appear on the appearance, and bubbles with a diameter of ≥0.3mm can often be detected, which will increase the probability of leakage and water rust corrosion, reduce the battery life and also pose safety hazards.
Laser cleaning technology can achieve high cleanliness on the surface of the battery cell, reaching Sa3 level, with a removal rate of more than 99.9%. Compared with traditional cleaning methods, laser cleaning has no stress on the surface of the battery cell, and can ensure that the physical and chemical indicators of the surface of the battery cell do not change to the greatest extent, thereby extending the service life of the battery. In addition, laser cleaning does not produce harmful pollutants, making it an environmentally friendly green cleaning method.
Laser cleaning application areas expansion
China's lithium battery laser equipment market size (100 million yuan) Year-on-year growth
The market size of lithium-ion laser equipment in 2021 was 10.13 billion yuan. Driven by the demand for new energy vehicles, the demand for lithium-ion laser equipment is expected to reach 22 billion yuan in 2025.
Shipments: Lithium-ion Batteries: Worldwide
Lithium ion batteries: Production: Monthly Value
Shipments Lithium ion batteries
Lithium ion batteries: Worldwide (GWh) Production: Monthly value(million pcs)
According to market research company QYR, by 2026, the global laser cleaning market will be close to US$745 billion, with a compound annual growth rate of about 4.3%.
According to public information, the United States has already maturely applied laser cleaning technology to the surface cleaning of F-16 fighter jets and C-130 transport aircraft; the surface cleaning technology of more than dozens of titanium alloy parts in the aviation engines produced by Rolls-Royce in the United Kingdom is laser cleaning.
China's laser cleaning technology is also continuing to develop. In 2016, China's first laser cleaning machine came out; in 2018, laser cleaning machines reached the 100-watt level; in 2019, fiber laser technology broke through 1000W...Continuously promoting the high-quality supply of innovative technologies in the laser industry chain, in addition to its application in the field of new energy power batteries, it is also used in tire and body surface painting, large oil stain cleaning of parts, etc.
Tire laser cleaning
With the development of new energy vehicles, stricter requirements are put forward for the control of tire noise. After laser cleaning, the wear and noise of new energy vehicle tires can be reduced, and the driving experience and comfort of drivers can be improved.
Compared with traditional cleaning methods, laser cleaning has the advantages of no consumables during the cleaning process and no damage to the tires; high cleaning efficiency and good consistency; automatic cleaning can be achieved, and the cost of use is only 1/10 of dry ice cleaning.
In the manufacturing process of silent tires, a focused high-energy laser beam is used to irradiate the surface of organic polymer materials, causing physical and chemical changes on the surface of the materials, thereby improving tire quality and production processes, improving the matching of tires and car bodies, and improving the overall performance of the vehicle. Laser cleaning can effectively remove residual release agents on the inner wall of the tire, and improve the coating effect of composite materials and the adhesion effect of polyurethane sponges.