Application of laser welding in the field of lithium batteries
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Lithium-ion batteries are widely used in various electronic devices (such as mobile phones, laptops, PDAs, digital cameras and digital video cameras, etc.) and transportation vehicles (patrol cars, electric bicycles, electric cars, etc.) due to the advantages of high specific energy, long cycle life, small self-discharge, no memory effect and no pollution, and have become a high-tech industry supported by China's energy sector.
Power batteries refer to batteries used in electric vehicles, which are secondary batteries with larger capacity and output power relative to small capacity batteries (e.g. mobile , laptop batteries, etc.) that can be used in electric vehicle drive power and large mobile power applications. Lithium-ion batteries or battery packs are made in a very large number of processes, and several of these processes, such as explosion-proof valve seal welding, lug welding, flexible connection welding, battery case seal welding, module and PACK welding all use laser welding as the best process. The main materials used for welding power batteries are pure copper, aluminium and aluminium alloy, stainless steel, etc.
batter pack
1&#;Battery explosion-proof valve welding
The explosion-proof valve of the battery is a thin-walled valve body on the sealing plate of the battery, when the internal pressure of the battery exceeds the specified value, the explosion-proof valve body ruptures to prevent the battery from bursting. The safety valve structure is ingenious and this process is extremely demanding on the laser welding process. Prior to continuous laser welding, battery explosion-proof valves were welded using pulsed lasers, which overlapped and covered joints to achieve continuous seal welding, but the welding efficiency was low and the seal was relatively poor. The use of continuous laser welding can achieve high speed and high quality welding, welding stability, welding efficiency and yield can be guaranteed.
2&#;Battery lug welding
The positive electrode of the battery is made of aluminium (Al) and the negative electrode is made of nickel (Ni) or nickel-plated copper (Ni-Cu). One part of the manufacturing process for power cells is the welding of the lugs to the poles. In the manufacture of secondary cells it is necessary to weld them together with an additional aluminium safety valve. The welding should not only ensure a reliable connection between the pole lug and the pole post, but also require a smooth and beautiful weld.
3&#;Battery pole strip spot welding
The materials used for the battery pole strip include pure aluminium strip, nickel strip, aluminium-nickel composite strip and a small amount of copper strip. With the emergence of the QCW quasi-continuous laser from IPG, it has been widely used in the welding of battery strips. At the same time, due to its good beam quality and small welding spot, it has unique advantages in dealing with the welding of highly reflective aluminium strips, copper strips and narrow strip battery strips (strip width below 1.5 mm).
4, power battery shell and cover plate sealing welding
Power battery shell materials are aluminum alloy and stainless steel, of which the use of aluminum alloy is the most, generally aluminum alloy, there are also a few pure aluminum. Stainless steel is the best material for laser welding, especially 304 stainless steel, either pulse or continuous laser are able to obtain the appearance and performance of good weld.
The laser welding performance of aluminium and aluminium alloys varies slightly depending on the welding method used. With the exception of pure aluminium and 3-series aluminium alloys, for which both pulsed and continuous welding is not a problem, continuous laser welding is the preferred method to reduce crack sensitivity. At the same time, according to the thickness of the power battery shell to choose the appropriate power of the laser, the general shell thickness of 1mm or less, can be considered to use a single-mode laser within W, the thickness of more than 1mm need to use more than W single-mode or multi-mode lasers.
Small capacity lithium batteries often use a relatively thin aluminum case (thickness of 0.25mm or so), there are also and so on using the steel case. Due to the thickness of the case, the welding of such batteries is generally done with a lower power laser. The use of continuous lasers for welding thin-case lithium batteries can increase efficiency by a factor of 5 to 10, and the appearance and sealing is better. Therefore there is a trend to gradually replace pulsed lasers in this application area.
5, power battery module and pack welding
Series and parallel connection between the power battery is generally completed by connecting the piece with the single battery welding, positive and negative pole materials are different, there are generally copper and aluminum 2 materials, due to the formation of brittle compounds between copper and aluminum after laser welding, can not meet the use of requirements, usually using ultrasonic welding outside, copper and copper, aluminum and aluminum are generally used laser welding. At the same time, as both copper and aluminium transfer heat very quickly and have a very high reflectivity to the laser, the thickness of the connection piece is relatively large, so a higher power laser is required to achieve welding.
Features of laser welded lithium batteries
From the manufacture of lithium battery cells to the formation of battery packs, welding is a very important manufacturing process. The conductivity, strength, gas tightness, metal fatigue and corrosion resistance of lithium batteries are typical criteria for evaluating the quality of battery welding. The choice of welding method and welding process will directly affect the cost, quality, safety and consistency of the battery. Laser welding has become the preferred solution for many welding tasks due to the advantages of safe and reliable welding, process precision and environmental protection.
Power battery, as the core component of electric vehicles, its performance directly affects the application of electric vehicles. For example, power battery performance is related to new energy vehicle&#;s safety, range, energy density, power density, working-life, etc..
As the production and sales of new energy vehicles continue to climb, the power battery industry also continues to benefit.
Laser welding, as a high precision welding method, extremely flexible, accurate and efficient, able to meet the performance requirements of the power battery production process, has become the standard equipment of the power battery production line.
Compared with traditional arc welding and electric resistance welding, laser welding has obvious advantages. For example, the welding joints are small and highly efficient, which makes it easy to automate the production of power batteries, while the yield rate of batteries is higher.
Lithium-ion Battery Laser Welding Applications
There are six main laser welding parts for lithium batteries.
They are the welding of the cover explosion-proof valve, the welding of the cell electrodes and pole, the welding of the battery shell, the welding of the sealing nail (electrolyte injection port), the welding of the cell electrodes, the welding of the cell electrodes and the top cover; in addition, the welding of the super capacitor is mainly based on the welding of the connecting piece and the negative electrode seal.
HGTECH is actively integrated into the new energy industry chain, and with years of experience in laser application, it has combined laser welding technology with automation and intelligent systems in power battery manufacturing to create a complete set of laser processing solutions and related supporting facilities, including automatic sealing line for battery cell cover, automatic sealing line for liquid injection port, automatic welding system for pole pillar soft connection, explosion-proof valve welding system and automatic welding system for battery pack, etc.
HGTECH&#;s Solutions For Li-ion Battery
Liquid-filled hole laser welding machine
This machine is used for automatic nail welding of steel-cased lithium ion battery cells; it mainly consists of a loading system, a transit system, a motor turntable clamping system, a wiping system, a CCD correction, positioning and detection system, a seal nail loading system, a laser welding system, an unloading system, a cooling system and a dust removal system.
Machine features
- Uniqueness: fully automatic equipment consisting of auto loading, nail loading and unloading, with CCD correction, positioning and inspection, and 4 one-mould, two-hole fixtures on a DD motor rotary.
- High production efficiency: Imported vibrating mirror processing, single fixture with two lines welding simultaneously, single machine ppm &#;20.
- High Compatibility: line changes for different sizes of products.
- High stability: stable operation for 7*24 hours.
- Safe and environmentally friendly: no waste water discharge problems.
If you are looking for more details, kindly visit Lithium Battery Explosion Valve Laser Welding Machine manufacturer.
Fully automatic sealing nail system
This workstation is used for the production of square power battery sealing nail welding, which can realize the process of battery input, laser measurement of height, cover sweeping, laser cleaning, sealing nail loading, laser welding, post-welding inspection and battery output.
Machine features
- Battery vertical input, flow line conveying.
- Transit loading/unloading flow line, 2 to 4 channels for loading and 4 to 2 channels for unloading.
- Bind pallet QC code with battery QC code, enabling the sharing of height measurement and positioning information across all processes, enabling the traceability and management of battery information.
- Automatic sorting of OK/NG products.
- Communication with customer MES systems for automatic product data upload and trace.
Fully automatic top-cover system
This welding line is used for the production of laminated square power battery&#;s top cover and shell welding, mainly including laser pre-spot welding equipment and laser peripheral welding equipment.
Machine features
- Battery vertical input, flow line conveying, automatic code scanning.
- Dual channel design, welding head with two channels switching, higher laser utilization.
- Peripheral welding fiber + semiconductor compound laser welding, higher welding quality.
- Automatic sorting of OK/NG products.
- Automatic product data upload and traceability with customer MES system.
Soft package module welding line
This equipment is used for Core pack welding, with functions such as Core pack clamping and positioning, Core pack caching, pole bending, laser welding, weld appearance inspection and weld internal resistance inspection.
Machine features
- Core pack clamping and positioning, core pack cache, pole bending, laser welding, weld seam internal resistance detection, weld seam length and width detection.
- Core pack automatic code scanning, pallet RFID automatic code reading, and data binding with process information.
- Core pack automatic clamping function.
- Various types of NG material output functions, core pack anti-drop function, and protection for man-machine safety.
- Automatic discharge of the core pack into the water tank in case of fire/smoke in the welding station.
- Communication with the customer's MES system for automatic uploading and tracing of product data.
Automatic assembly and welding machine for soft pack modules
This welding machine is suitable for the assembly, welding and inspection of battery modules of different structures and sizes, such as soft pack modules.
Machine Features
- Automatic clamping of Core packs.
- Core pack automatic code scanning and data binding with process information.
- Complete set of processes such as Core pack clamping and positioning, loading, total positive and negative assembly, FPC installing, pre-solder CCD inspection, post-solder CCD inspection, internal resistance test etc.
- With all kinds of NG material output function and core pack anti-drop function, protection for man-machine safety.
- Automatic discharge into water tank while core pack soldering station fire/smoke
- Communication with the customer's MES system to automatically upload and trace product data.
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