Super full analysis | Here is a one-stop efficient solution for lithium battery cleaning and frosting

As the global demand for new energy vehicles increases dramatically, the demand for power batteries, which are its core components, also increases. The preparation process of power batteries, including pole piece manufacturing, cell synthesis and module production, faces new challenges. In this context, laser cleaning and texturing technology has been widely used in battery manufacturing due to its advantages of high efficiency, precision, flexibility, reliability, stability, no loss, automation and high safety.

Application of laser cleaning in power battery production

The development of lasers is an important factor in promoting laser cleaning and texturing processes. GZTECH is committed to the research and development of fiber MOPA pulse lasers, and has launched 100W-2000W highly stable and adjustable nanosecond pulse MOPA lasers, which are suitable for all cleaning and texturing processes in power battery production, providing customers with a one-stop solution.

• Removal of coating on the electrode surface

Before welding, the coating on the surface of the pole ear needs to be removed. The current methods for removing the coating mainly include mechanical scraping, foam glue and laser removal. However, mechanical removal is very easy to scratch the pole piece, and it cannot be guaranteed to be completely removed; foam glue has many processes, high production costs, and is not applicable to anode water-based materials. Laser has the advantages of being green, efficient, and non-damaging to copper foil. It is recognized as the preferred method for removing the coating of lithium battery pole pieces.

In view of the requirements of no residue and no damage for the cleaning of power battery pole pieces, Guangzhi Technology's YFPN-250-GM model laser has up to 15 pulse width options from 10 to 500ns. It adopts a layer-by-layer removal process to ensure that the coating is completely removed and the foil is not damaged. After reasonable experimental design and verification, a better cleaning effect was obtained.

Examples of good anode cleaning results and defective quality

    Examples of good cathode cleaning results and defective quality

Anode coating removal (10x30mm2 1.5s) Cathode coating removal (10x20mm2 1.2s)

• Electrolyte cleaning of injection hole

The main process of cleaning the electrolyte is after the power battery is filled with liquid and before the sealing nail is welded. In order to ensure a good welding effect, the residual electrolyte on the filling port must be removed before welding. At present, the market mainly uses optical fiber infrared laser to avoid the sealing nail for cleaning, which has problems such as the glue nail is easy to melt and there is electrolyte residue. The subsequent welding electrolyte is easy to volatilize when heated, affecting the welding effect. In addition to infrared MOPA lasers, GZTECH also has 100~200W optical fiber green light lasers, which use green light to clean the entire surface of the filling hole, leaving basically no residue, and the glue nail has little impact.

Power battery square shell cover

Green light cleaning                                 Fiber Optic Cleaning                             

• Cleaning of pole oxide layer

The connection of the poles on the battery cover can be divided into internal and external connections. The internal connection is the welding of the battery cell tabs and the poles on the cover; while the external connection is the welding of the battery poles through the connecting pieces to form a series and parallel circuit to form a battery module. Before welding, the oxide layer on the poles needs to be removed to ensure a good welding effect.

Comparison of pole cleaning before and after

Using laser to remove the surface oxide layer can significantly reduce the pole contact resistance and significantly improve the welding yield. Compared with traditional manual grinding methods, laser cleaning can more than double the corrosion resistance of the pole surface, and also has advantages in cleaning efficiency and cost. GZTECH YFPN-200-GM has been tested and its cleaning efficiency can reach <2 seconds/piece.

• Battery case frosting

In the traditional lithium battery production process, the insulation protection of the battery cell is usually isolated by a blue film (blue film). However, this material is prone to produce bubbles during packaging, and these bubbles are easy to burst during the use of the battery, resulting in abnormal discharge of the battery, thereby reducing the overall qualified rate of the battery. In contrast, UV spraying technology has begun to be widely adopted by battery manufacturers due to its excellent environmental protection characteristics, high production efficiency and high yield rate. Before spraying, in order to improve the adhesion of the paint to the shell, the shell needs to be roughened to improve the surface roughness of the shell. According to the characteristics of laser roughening, GZTECH has developed and launched multiple types of 1000W pulse lasers to meet the different needs of customers.

Comparison of battery shell forsting solutions

Roughness measurement

Micrographs

Square battery shell frosting

Cylindrical battery frosting (aluminum shell)

Cylindrical battery frosting (steel shell)

• Blue film and blue paint cleaning

During the manufacturing process of power batteries, the blue paint or blue film on the surface of the battery box may have defects such as bubbles, wrinkles, and uneven coating. These problematic batteries need to be repaired, that is, the blue paint or blue film is removed and reprocessed. The 1000W square spot pulse laser can not only complete the battery shell roughening, but also realize the blue film and blue paint repair process, so that one laser can be used for multiple purposes, truly reducing costs and increasing efficiency for customers.

Blue paint cleaning

Blue film softening

• Other cleaning before and after welding

In the production process of power batteries, the cleaning of the CMT weld of the battery pack tray, the electrophoretic paint of the battery water cooling plate, the oxide layer of the battery pack box, and the oxide layer before welding of the protective bottom plate all affect the safety performance of the battery pack. For the above cleaning processes, GZTECH can provide 200W~1000W pulsed fiber lasers. Customers can flexibly choose the corresponding laser cleaning solution according to their specific efficiency requirements.

CMT Weld Cleaning

Water cooling plate paint removal

Cleaning of copper bars before welding