Electrical Modelling and Investigation of Laser Beam Welded Joints for Lithium-Ion Batteries

Abstract

The growing electrification of vehicles and tools increases the demand for low resistance contacts. Today’s batteries for electric vehicles consist of large quantities of single battery cells to reach the desired nominal voltage and energy. Each single cell needs a contacting of its cell terminals, which raises the necessity of an automated contacting process with low joint resistances to reduce the energy loss in the cell transitions. A capable joining process suitable for highly electrically conductive materials like copper or aluminium is the laser beam welding. This study contains the theoretical examination of the joint resistance and a simulation of the current flow dependent on the contacting welds’ position in an overlap configuration. The results are verified by examinations of laser-welded joints in a test bench environment. The investigations are analysing the influence of the shape and position of the weld seams as well as the influence of the laser welding parameters. The investigation identifies a tendency for current to flow predominantly through a contact’s edges. The use of a double weld seam with the largest possible distance greatly increases the joint’s conductivity, by leveraging this tendency and implementing a parallel connection. A simplistic increase of welded contact area does not only have a significantly smaller effect on the overall conductivity, but can eventually also reduce it.

Review on Li-Ion Based Battery Chemistry: Challenges and Opportunities

“…BEVs using LiMn2O4 cathodes lessen environmental difficulties (consumption of energy, air pollutants, such as GHGs), however material manufacture, construction, and reprocessing of automobile batteries of Li-Ion in hybrid electrical vehicles are still in their infancy. Hollatz S et al [39] deliberated the consumption of energy and release of air, produced during the recovery of LiMn2O4, aluminium, and Cu using three different recovering methods (recycling by direct physically, intermediate physical recycling, and hydrometallurgical), as well as the outcome(s) of locked-loop recovering on the battery production's environmental effects. The biggest problem with Li-ion batteries is that they generate a lot of heat during the charging / discharging process, which causes battery pack temperature to increase, especially at higher working currents.…”

“…Using a unified methodology, researchers developed a framework for generating similar models of circuit that can properly mimic the multi-physics phenomena of LIB packages, including cooling arrangements with liquid. Hollatz et al [39] investigated a predisposition for current to flow mostly near the edges of a contact by influencing the predilection and establishing a corresponding linking using a dual joint stratum with the longest plausible spacing considerably enhances linkage conductivity [44]. Kwak et al [40] examined recent findings as well as advances in cathode and anode metal, electrocatalysis on surfaces, in the solution phase of electrolytes, and the singlet oxygen atom's degradative effect, is often generated in Li-O2 cells [45].…”

Overview of Optical Digital Measuring Challenges and Technologies in Laser Welded Components in EV Battery Module Design and Manufacturing

“…Online process monitoring of battery joining process is effective method to avoid welding errors leading to joint failures [14]. In addition to the consideration of safety aspects of the individual cell components, pack-level safety features should also be met [31]. For example, when considering the safety of Li-ion packs, various modes of heat propagation from thermal runaway location to other cells need to be investigated.…”

Lithium-Ion Batteries: Latest Advances and Prospects

“…In response to this call, twelve research papers [19][20][21][22][23][24][25][26][27][28][29][30] and one case report [31] were thoroughly peer-reviewed and published. The published research papers covered advances in several fronts of the technology, including detailed fundamental studies of the electrochemical cell and investigations to better improve parameters related to battery packs.…”

“…A capable joining process suitable for highly electrically conductive materials like copper or aluminum is laser beam welding. In the research paper published in this Special Issue, a theoretical examination of the joint resistance and a simulation of the current flow dependent on the contacting weld's position in an overlap configuration was performed [28]. This investigation highlighted the influence of the shape and position of the weld seams as well as the laser welding parameters, and how these parameters can be leveraged to further reduce the cell-to-cell joint resistances.…”