Current Status and Challenges of Laser Welding Electric Vehicle Batteries

The automotive industry is beginning to undergo major technological changes. Toyota Prius, Honda Insight, Chevrolet Volt and Nissan Leaf are the first electric vehicles on sale. In the next three years, all major automakers and some newly established companies will introduce some form of hybrid, plug-in hybrid or electric vehicles to the consumer and commercial markets. Although the internal combustion engine will still dominate the market in the next few years, as the cost of hydrocarbon fuel increases, electric drive systems will gain market share.　　 Electric drive systems in electric vehicles require new lithium-ion battery technology. Although lithium batteries have been used in mobile phones and notebook computers for many years, batteries used in vehicles must provide great power for the system. The service life of these drive systems cannot be less than ten years. In order to be able to compete with internal combustion engines in cost, the battery system also needs to reduce the cost to more than half of the current cost. Only reliable and inexpensive new manufacturing methods can meet these needs.　　The current status of the industry in joining technology 　　EWI has been cooperating with advanced battery companies for several years and is committed to this challenge. At the battery manufacturing technology seminar held in September 2010, EWI surveyed the industry on the connection technologies currently used in the assembly of batteries and battery packs (see Table 1). The results show that because lithium-ion batteries are composite components of multiple layers of materials (copper, aluminum, nickel, and nickel-plated copper) with varying thicknesses (0.001 to 0.0625 inches), the manufacture of such batteries requires the assembly of a large number of parts, including different materials. Between the seams. To assemble these parts, the industry uses various processes, including brazing, resistance, ultrasonic and laser welding. The survey results in Table 1 show that none of the joining processes dominates. There is no single process that has been approved by people and can be used for geometric assembly of various materials.　　 After this investigation, EWI and the Ohio State University Automotive Research Center set up a project to investigate the resistance, ultrasonic and laser welding processes of the combination of materials that connect and assemble lithium-ion batteries and battery packs. The purpose is to study the data and help the industry find a process to connect the various components in the assembly.