The Fraunhofer Institute for Laser Technology ILT has developed a new laser welding technology for temperature-sensitive cylindrical battery cells that is now ready for series production. Since 2009 the experts from in Aachen, Germany have been working on battery joining – the process of connecting individual cells into packs. They are currently working with other Fraunhofer Institutes to put together a complete battery pack.
The all-important joining process is carried out using fiber lasers with a maximum power output of 1 kW. The method is called oscillation laser welding, a technology that applies a precise energy input to the batteries.
It does so by superimposing a circular or swinging oscillation of the laser beam onto the feed movement. This local modulation allows the control of the welding process very successfully. What’s more, it enables the scientists to carry out circular welding on the tops of the batteries.
Welding 4,800 cells
As the metals are melted during the laser-welding process, a very small area (0.1 to 0.25 mm) is briefly heated to a high temperature, only to rapidly cool again once the welding is over. “Take notebook cells, for instance. Here, we weld very thin steel plates to copper alloys directly over temperature-sensitive plastic,” Benjamin Mehlmann, expert for the metallic materials micro-joining at the Fraunhofer ILT explains.
“What makes this possible is that the method is incredibly fast and has a low energy input.” Preferred applications for these round cells include portable computers, power tools (such as electric screwdrivers), and non-standard electric cars (such as the Tesla Roadster).
Oscillation laser welding is currently being used to join 4,800 standard cells (each with a diameter of 18 mm and a height of 65 mm) into a battery pack suitable for use in an electric vehicle. The Aachen-based scientists weld the cells in their charged state, which makes safety of paramount importance as the cells contain electrolytes that must not be allowed to leak out.
Optimizing oscillation laser welding
Fraunhofer ILT is currently in the validation phase of the project, which sees Mehlmann and his team improving the process and making it safe to use. As Mehlmann explains: “It’s an interesting option for SMEs wanting to use the method to develop their own solutions for portable and stationary applications.”
Integrating the process into a conventional ribbon bonder is also part of the brief (ribbon bonding is an assembly and joining technology process for bonding metallic ribbon, usually with ultrasound, to electrically connect components). Central to this application is the electrical contact between battery and electronics.
This development came about in a publicly funded project that saw Fraunhofer ILT collaborating with F & K Delvotec GmbH, a company based in Ottobrunn. Both parties will be showcasing the prototype at F & K Delvotec GmbH’s booth at the SMT Hybrid Packaging trade fair in Nuremberg, Germany, (May 5 – 7, 2015, Booth 7A-330).
Fraunhofer ILT will be presenting this joint project on April 27-29 at its booth (no. 25) at the Battery Power conference at the Eurogress in Aachen, Germany.
Dipl.-Ing. Benjamin Mehlmann
Micro Joining Group
Telephone +49 241 8906-613
Dr.-Ing. Alexander Olowinsky
Head of the Micro Joining Group
Telephone +49 241 8906-491
Fraunhofer Institute for Laser Technology ILT
52074 Aachen, Germany
Petra Nolis | Fraunhofer-Institut für Lasertechnik ILT
New technology for mass-production of complex molded composite components
23.01.2017 | Evonik Industries AG
Etching Microstructures with Lasers
25.10.2016 | Fraunhofer-Institut für Lasertechnik ILT
For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.
According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
23.01.2017 | Health and Medicine
23.01.2017 | Physics and Astronomy
23.01.2017 | Process Engineering