Battery manufacturing industry is increasingly becoming the biggest 21st century challenges. Although the global annual production capacity battery has reached tens of billions of pieces, but the traditional battery manufacturing technology and cost effectiveness in the battery budget, can not meet the rapid growth of the battery applications. Most of us have been very clear, the battery used in hybrid vehicles, plug-in hybrid electric vehicles and all vehicles. Although the batteries in automotive applications mixed, but still can not stop the people in this industry to invest. "American Recovery and Reinvestment Act" (ARRA or AR2) mentioned to those in the U.S. investment company producing cells into the tens of millions of dollars. Borrow U.S. Energy Secretary Steven Chu (Steven Chu) as saying, "These are very effective investment in the future will bring us many times in return, mainly reflected in: the creation of employment opportunities, reduce dependence on foreign oil, we breathe air cleaner, and the impact the fight against climate change. "
In addition to applications in the automotive industry, the cost-effective, high-performance battery power and alternative energy industry in the application are also very attractive. Widespread installation of battery storage to provide residential power demand load levels, and emergency backup power. This distributed energy storage solutions can also improve the efficiency of electricity production base of production, to offset part of the demand for investment, to improve some of the large grid infrastructure. Moreover, the electrical energy storage will help give full play to the advantage of alternative energy sources of instability, such as solar and wind power. In addition, the economic and high-performance battery technology will also help reduce the cost of grid expansion.
Today, the "high performance and economy" should be used to clearly describe and approved batteries in helping us solve the energy challenge in playing the hero role. While so far a lot of development work focused on new battery technology developed and mature before the old technology (such as for flashlights, cameras and computer battery), compared also slightly tender. Because the application is now on the market for battery energy storage and battery life requirements are higher, the battery's weight and lower cost requirements, the challenges of the manufacturing process is still addressed. Many promising battery solutions exist only in theory, graphic design, CAD, and this approach has been designed and existing manufacturing capabilities and limitations faced by divorced. In other words, designers and manufacturing personnel to communicate between the need for more! We will help them.
Many applications in the industry in battery technology, has no recognized or obvious winner. Lithium ion, nickel metal hydride, zinc-air, sodium, sulfur, and many other battery chemistries competing with each other to meet the diverse needs of a variety of applications. And the battery for a given species, there are many different products will change shape, which may lead to different manufacturing methods. New batteries are mostly cylindrical or graphic design. Battery cells are stacked, packed up, or arrays, so that the separate units are combined in series and parallel circuits. The connection between unit and unit may involve similar or different metal materials, there are two or more different layers. Despite the diversity of design, but in all of these concepts in battery design have one thing in common emerging. The common challenge is the need to increasingly thin metal material at a faster speed link, which is laser applications.
Battery usually contains many kinds of materials, such as zinc, steel, aluminum, copper, titanium and nickel. These may be made of metal electrodes, wire, or just a shell. They may be or not be a metal or other material covering the battery. However, no matter by what their composition, based on weight and cost minimization considerations, they should be as thin as possible. Many new battery design material thickness in the range 25 to 250 microns. Welding of these metals are two main requirements include creating a current conduction path and / or electrolyte can be stored, but the design and application of each battery, the battery's full performance specifications welding is unique. Conductivity, strength, hermetic, metal fatigue and corrosion resistance is typical of the welding quality evaluation criteria. Then, all of these criteria have been identified and achieved, the key determining factor is whether the economic cost.
Battery welding design for the success of the manufacturing process plays a key role. Fillet welding and butt welding is often attractive to the designer, but take the welding is by far the most likely to succeed. Lap welding welding compared to the other two methods, can provide more flexibility, thanks to its need to implement other means of welding required precision alignment of the node to the end of the beam. Lap welding but also for the final task of providing integrated multi-cell module of the possibility of welding (see Figure 1), this process may involve one or more material types. For example, a same type of metal may need to be accurately welded to another type of conductor. Welding methods can be used now there are many kinds, and is rapidly developing.
Bath series electrical connection and (BUSS) connections are usually required to connect non-similar metals. It is in this area, the unique high-speed laser welding (100-1000 mm / sec) is the other welding technology can not match. High-brightness fiber laser further promote high-speed welding, the weld can be achieved at low heat input and high solidification rate. This high cooling rate can effectively control the mixture of metal welded in place in the coagulation defects. Most likely to crack a combination of weld metal is copper and aluminum, which also happen to be in the lithium-ion battery in one of the most commonly used combinations of metals. High-speed fiber-optic laser welding of metal welding in this important process, showing a crack-free welding characteristics. Need to use or some other unusual combinations of metals can also use laser welding to complete, especially when the solidification rate is high time (see Figure 2). Finally, as long as the weld metal combinations can be achieved, it is vital that they are expected to assess the performance of the battery capacity of the application (especially strength, toughness, fatigue and corrosion in the metal).
Some people may think, this attractive advantages and opportunities of the manufacturing process must be accompanied by a combination of negative factors. The first factor is the negative of these unique application of laser welding cell designers is relatively unfamiliar. Thus, the "laser friendly" design is not often as the preferred welding. In addition, if we consider the use of laser welding technology, which often occurs, the outstanding issues will emerge - the performance of the weld how? Battery industry seem to be more willing to quickly put into reliable manufacturing capacity, the simple point of view, society in no time, resources or patience to evaluate, develop and implement new alternative solutions.
There is a recognized, are frequently used for laser welding solution is based on the galvanometer scanning laser welding. This "remote welding" technology in the vast world of laser welding is not particularly novel, but in the scan head and laser performance improvements, is it more and more attention. The increasing power of high-power fiber laser beam emitted almost perfect, now in the welding process is completely within the speed limit full use of, and limits the movement of other welding systems to accelerate the problem did not affect it. The beam quality is also guaranteed a greater visual range, a longer run time and greater angle of incidence, can be configured in a number of batteries used to weld multiple joints simultaneously welding (see Figure 3).
Other high-speed galvanometer scanning laser welding advances include the new "flying optics" welding technique. In this case, the need to achieve broad coverage, high welding speed and acceleration are all very high precision of synchronization through the scanning axis (A, B) and perpendicular direction of mechanical motion (X, Y) to achieve. EWI company uses a standard scan head and Aerotech Scanlab produced by the beta CNC software and hardware to develop and prove the feasibility of this technology. This high-performance solution for laser welding (see Figure 4) is currently used for battery and fuel cell welding welding challenges in the development.
flexible cable tray, mesh cable tray, metal cable tray
The last problem is the process of laser welding cell stability and quality assurance. Based on the speed and flexibility of laser welding, the manufacturing process also depends on the success of other mechanical parts in the whole system performance, to quickly achieve a good weld. This is a very difficult task, especially considering the small size and high speed welding, and battery manufacturing large quantities required to complete the weld. At the same time, taking into account in the final welding of the battery package requires the number of Six Sigma quality level of welding is not enough, need to achieve higher quality levels. For these key challenges (and welding quality assurance process route) solutions, mostly through high-speed image acquisition and analysis available. Some of these methods have in some lower-speed laser welding applications try, but need to further improve the speed and accuracy, which is in the battery manufacturing industry in the potential of laser welding full assurance.
Welding speed, mixed-metal performance and quality control has had the chance, only due to the further development and widespread use. Laser welding may only capture this round of new battery development boom in a small, but it may become the next most dominant cell materials selection connectivity applications.
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