{"id":3668,"date":"2025-03-24T12:29:21","date_gmt":"2025-03-24T12:29:21","guid":{"rendered":"https:\/\/intouchray.com\/?p=3668"},"modified":"2026-05-06T19:34:57","modified_gmt":"2026-05-06T11:34:57","slug":"laser-welding-application-in-electric-vehicles-power-batteries","status":"publish","type":"post","link":"https:\/\/www.intouchray.com\/eo\/laser-welding-application-in-electric-vehicles-power-batteries\/","title":{"rendered":"Laser welding application in electric vehicles: power batteries"},"content":{"rendered":"

Today, we share the application of laser welding technology in electric vehicle-power battery, mainly including battery electrode ear-bus welding, battery shell welding, etc., involving Al-Fe, Al-Cu, Cu-Fe and other different-material welding.<\/strong><\/strong><\/p>\n

01<\/strong><\/strong><\/p>\n

Application background<\/strong><\/strong><\/p>\n

In the context of global warming and greenhouse gas emission reduction, new energy vehicles, especially electric vehicles, are rising rapidly. The manufacturing of its core component-battery system, requires strict welding technology, mainly because the battery system has complex structure, including a variety of materials and complex connection. Traditional welding methods, such as ultrasonic welding and resistance spot welding, have limitations in dealing with the connection of battery electrode materials (such as aluminum, copper and steel). For example, ultrasonic welding is not suitable for the common battery structure of electric vehicles, and the resistance spot welding is difficult to weld due to the high conductivity of aluminum and copper.<\/p>\n

Laser welding technology is an ideal choice for its non-contact, high energy density, precise thermal input control and easy automation. It can meet the welding needs of different materials of battery system, such as aluminum steel, copper aluminum, copper steel welding between battery electrode and bus, and aluminum \/ steel battery shell welding, which plays a key role in ensuring the reliability of connection, and improving battery performance and safety.<\/p>\n

02<\/strong><\/strong><\/p>\n

Power battery type<\/strong><\/strong><\/p>\n

Power battery type<\/strong><\/p>\n

\u2460 Small cylindrical battery (e. g. model 18650), standardized size, safety and relatively cheap cost;<\/p>\n

\u2461 Large prism batteries, which perform well in terms of energy density and stability;<\/p>\n

\u2462 Soft-coated polymer battery, prone to geometry when charging.<\/p>\n

* Battery type<\/p>\n

\"Laser<\/figure>\n

The battery pack is composed of multiple batteries in series or in series and parallel, which are connected through busbars. The working environment is complex, and the connection reliability directly affects the performance and safety of the battery system.<\/p>\n

* Battery pack structure a) cylindrical battery b) prismatic battery<\/p>\n

\"Laser<\/figure>\n

Limitations of common welding techniques<\/strong><\/strong><\/p>\n

supersonic welding<\/strong><\/strong><\/p>\n

Mainly uses high frequency vibration (usually 20 kHz and above) to make the material form a solid bonding under pressure to achieve the connection.<\/p>\n

\u2460 This method is suitable for welding thin foil, different materials or high conductive materials, mainly applied to strip batteries.<\/p>\n

\u2461 Electric vehicle batteries are usually cylindrical or prismatic batteries, which may destroy the integrity of the battery structure under the combination of pressure and vibration, so ultrasonic welding is not suitable for the battery welding of electric vehicles.<\/p>\n

resistance spot welding<\/strong><\/strong><\/p>\n

The working principle is mainly to apply pressure on the contact surface of the workpiece, and to use a large current to melt the parts locally. However, the common materials of electric vehicle batteries are aluminum and copper, which have the characteristics of high electrical conductivity and thermal conductivity, making it difficult to weld the resistance spot welding.<\/p>\n

03<\/p>\n

Battery pole ear is welded with the bus<\/strong><\/strong><\/p>\n

Welding characteristics<\/strong><\/p>\n

Material combination: the battery pole ear material is often aluminum, copper or steel, the bus material is mostly copper or aluminum, forming aluminum-copper, aluminum-steel, copper-steel and other combinations.<\/p>\n

High performance requirements: the welding site should ensure low resistance, high conductivity and good mechanical strength, in order to ensure the battery charge and discharge efficiency and long-term stability.<\/p>\n

* Pole ear and bus of soft pack \/ cylindrical battery<\/p>\n

\"Laser<\/figure>\n

Aluminum-steel laser welding<\/strong><\/strong><\/p>\n

Welding difficulties:<\/strong><\/strong><\/p>\n

\u2460 Aluminum and steel thermal properties are very different, welding will form brittle metal intermetallic compound (IMC), such as Fe\u2082Al\u2085, Fe\u2084Al\u2081\u2083, etc., affect the microstructure, electrical performance and thermal performance of the joint, increase the internal resistance of the battery, shorten the service life.<\/p>\n

\u2461 IMC generation should be controlled during welding.<\/p>\n

    \n
  1. Control process parameters<\/strong><\/li>\n<\/ol>\n

    \u2460 Control the thermal input: adjust the laser power, welding speed and pulse parameters (frequency, duty ratio), balance the melting depth and the size of the thermal influence area, and reduce the IMC generation.<\/p>\n

    \u2461 Optimize pulse waveform: special pulse waveform is used to change the thermal cycle characteristics, such as slow rise and slow drop waveform to reduce the temperature gradient and thermal stress, and inhibit the rapid cooling leading to a large number of brittle IMCs generation.<\/p>\n

      \n
    • Use the middle layer<\/strong><\/li>\n<\/ul>\n

      \u2460 Composition: nickel selection, silicon based alloy and other intermediate layer materials, because of its reaction with aluminum steel. Nickel improves wetting and element diffusion, and the toughness of nickel-containing IMCs is better than that of aluminum steel. Si in the Al-Si compounds) affects the growth of Fe-Si compounds optimizes the mechanical properties of the joint, and the Si content is fine-adjusted according to the material and process requirements.<\/p>\n

      \u2461 Thickness: \u03bc m to tens of \u03bc m thickness range can effectively adjust the formation of IMMC, improve joint performance and reliability.<\/p>\n

        \n
      • Magnetic field auxiliary<\/strong><\/li>\n<\/ul>\n

        \u2460 Magnetic field direction: The vertical magnetic field inhibits the macroscopic diffusion of elements in the melt pool, changes the convection and crystallization morphology, and reduces the excessive fusion of Fe and Al to form brittle IMCs; the parallel magnetic field affects the micro-diffusion of solute and grain boundary migration, and refines the grains and optimizes the distribution and orientation of IMCs.<\/p>\n

        \u2461 Multi-field collaboration: combined with magnetic field and ultrasound, magnetic field collaboration and ultrasonic vibration to refine grains, remove stomatal inclusions, and improve the IMC structure. Ultrasonic vibration is helpful to break dendrites and uniform composition, magnetic field guides the direction of metal liquid flow and crystal growth, improve the solidification behavior and tissue uniformity of the molten pool, reduce the brittleness of IMC, and improve the toughness and electrical conductivity of joints.<\/p>\n

        * Laser swing welding aluminum-steel (swing amplitude 0.2-1.2mm)<\/p>\n

        \"Laser<\/figure>\n

        * Micromorphology of stainless steel \/ aluminum alloy joint a) Ni foil b) no Ni foil<\/p>\n

        \"Laser<\/figure>\n

        Copper-aluminum laser welding<\/strong><\/strong><\/p>\n

        Welding difficulties:<\/strong><\/strong><\/p>\n

        Copper and aluminum have different melting points, thermal conductivity and thermal expansion coefficient, forming Cu \u2082 Al and Cu\u2084Al\u2083 IMC by welding, which affect the microstructure and mechanical properties of welds, and need to inhibit their formation and growth.<\/p>\n

          \n
        1. Optimization of welding parameters<\/strong><\/li>\n<\/ol>\n

          \u2460 Matching high welding speed with low laser power can reduce the thermal input time and strength, and inhibit the formation of a large number of IMC. For example, during high-speed welding, CuAl \u2082 and other compounds are significantly reduced.<\/p>\n

          \u2461 Optimize the pulse frequency and duty cycle, change the atomic diffusion and reaction dynamics conditions of Cu and Al, make the IMC grow orderly and evenly distributed, and improve the joint performance.<\/p>\n

            \n
          • Fill silver, nickel and tin are made of silver, nickel and tin-based filling materials or specific alloy welding wire, which can melt the filling gap and dilute the base material elements, slow down the direct reaction of Cu and Al, and reduce the generation of brittle IMC.<\/li>\n<\/ul>\n

            For example, containing tin filling material, welding to form Cu\u2086Sn\u2085 and Cu\u2083Sn phases, change the tissue form of the joint, reduce the overall brittleness, improve the strength and toughness.<\/p>\n

              \n
            • Beam modulation uses beam oscillation, rotation or beam splitting and other modulation techniques to change the distribution of laser energy and the mode of action.<\/li>\n<\/ul>\n

              * Cu-Al SEM diagram (1500W, 30 mm\/s)<\/p>\n

              \"Laser<\/figure>\n

              Copper-steel laser welding<\/strong><\/strong><\/p>\n

              Welding difficulties:<\/strong><\/strong><\/p>\n

              The physical properties of copper and steel are very different, and the liquid phase separation and thermal cracks are prone to occur during laser welding, such as Cu infiltration into the steel grain boundary, leading to thermal cracks.<\/p>\n

                \n
              1. Laser offset<\/strong><\/li>\n<\/ol>\n

                The welding quality can be effectively improved by deflecting the laser to the copper side.<\/p>\n

                \"Laser<\/figure>\n
                  \n
                • Beam oscillations<\/strong><\/li>\n<\/ul>\n

                  Under the condition of annular beam oscillation of pure copper and stainless steel, the crack resistance of weld can be effectively improved. During the solidification process, the increase of the grain boundary significantly reduces the stress concentration and effectively controls the joint strength and deformation.<\/p>\n

                  * Unoscillating with an oscillating SEM<\/p>\n

                  \"Laser<\/figure>\n

                  04<\/p>\n

                  Battery shell welding<\/strong><\/strong><\/p>\n

                  * Tesla 4680 Battery<\/strong><\/p>\n

                  \"Laser<\/figure>\n

                  Laser welding of aluminum battery shell<\/strong><\/strong><\/p>\n

                  Due to its high thermal conductivity and large thermal expansion coefficient, aluminum alloy welding is easy to show cracks and pore defects; the surface oxide film and impurities are easy to decompose at high temperature, making the gas difficult to escape and cause pores.<\/p>\n

                    \n
                  1. Laser beam focus rotation + vertical oscillation<\/strong><\/li>\n<\/ol>\n

                    Laser welded 1060 aluminum alloy uses vertical oscillation to optimize the weld surface, reducing the porosity by 91% at a radius of 0.45mm.<\/p>\n

                    * Laser beam focus rotation and vertical oscillation SEM<\/p>\n

                    \"Laser<\/figure>\n
                      \n
                    • Spot shaping (four-beam)<\/strong><\/li>\n<\/ul>\n

                      The light spot shaping is four-beam welding, which increases the size of the small hole in the molten pool, stabilizes the metal vapor, reduces the splatter and pores, and improves the weld quality.<\/p>\n

                      * Schematic diagram of four beams<\/p>\n

                      \"Laser<\/figure>\n

                      Steel battery shell by laser welding<\/strong><\/strong><\/p>\n

                      The welding of austenitic stainless steel is prone to thermal cracking, which is related to the alloy composition and impurity content. The problem of thermal cracking can be effectively solved by adjusting the process parameters.<\/p>\n

                      arouse:<\/strong><\/strong><\/p>\n

                      \u2460 At present, the commonly used laser welding wavelength is mostly 1064nm, using blue laser \/ green laser welding heterogeneous materials may have a good effect.<\/p>\n

                      Specification Comparison<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n
                      Specification<\/th>\nSingle-Module Fiber Laser<\/th>\nMulti-Module Fiber Laser<\/th>\n<\/tr>\n<\/thead>\n
                      Maximum output power<\/td>\n1.5\u20134 kW<\/td>\n6\u201320 kW<\/td>\n<\/tr>\n
                      Wavelength<\/td>\n1070 nm<\/td>\n1070 \u00b1 10 nm<\/td>\n<\/tr>\n
                      Beam parameter product (BPP)<\/td>\n1.2\u20132.0 mm\u00b7mrad<\/td>\n2.5\u20134.0 mm\u00b7mrad<\/td>\n<\/tr>\n
                      Welding penetration depth (aluminum)<\/td>\n1.0\u20132.5 mm<\/td>\n3.0\u20138.0 mm<\/td>\n<\/tr>\n
                      Welding speed (0.3 mm copper busbar)<\/td>\n80\u2013120 mm\/s<\/td>\n150\u2013250 mm\/s<\/td>\n<\/tr>\n
                      Spatter rate (0.5 mm Al alloy)<\/td>\n2\u20135 mg\/m<\/td>\n1\u20133 mg\/m<\/td>\n<\/tr>\n
                      Power consumption at full load<\/td>\n5\u20138 kW<\/td>\n25\u201360 kW<\/td>\n<\/tr>\n
                      Typical system cost (laser source only)<\/td>\n$25,000\u2013$45,000<\/td>\n$80,000\u2013$200,000<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                      Frequently Asked Questions<\/h2>\n

                      What is the typical weld penetration depth required for copper busbars in EV power battery packs?<\/h3>\n

                      For high-current copper busbars (e.g., connecting prismatic cells), our Intouchray laser welding systems achieve a consistent weld penetration depth of 2.5 mm \u00b10.1 mm, ensuring a joint resistance below 0.05 m\u03a9 for optimal conductivity and mechanical strength.<\/p>\n

                      What is the maximum weldable aluminum alloy thickness for battery tab welding?<\/h3>\n

                      Our fiber laser welders can reliably join aluminum alloy 1050 tabs up to 3.0 mm thick to battery terminals, with a tensile strength exceeding 120 MPa and a cycle time of 0.8 seconds per weld.<\/p>\n

                      What is the required laser power for welding 0.2 mm nickel-plated steel tabs to lithium-ion cells?<\/h3>\n

                      For 0.2 mm nickel-plated steel tabs, our standard configuration uses a 500 W single-mode fiber laser, achieving a weld depth of 0.35 mm at a speed of 150 mm\/s, with a positional accuracy of \u00b10.02 mm.<\/p>\n

                      What is the typical cost per weld for a cylindrical 18650 cell terminal connection?<\/h3>\n

                      For high-volume production (over 1 million welds per year), the cost per weld drops to approximately $0.008 USD, including laser energy, shielding gas (argon at 15 L\/min), and consumables, with a weld diameter of 1.5 mm.<\/p>\n

                      What level of weld seam porosity is acceptable for battery pack safety?<\/h3>\n

                      Our process guarantees a porosity rate of less than 2% by area per weld cross-section, as verified by X-ray inspection, which is critical to prevent electrolyte leakage and maintain a cycle life of over 2,000 charge-discharge cycles.<\/p>\n

                      What is the maximum production throughput for a single laser welding station on prismatic cell modules?<\/h3>\n

                      With our dual-beam scanning head, a single Intouchray station can weld 120 busbar connections per minute, handling modules up to 600 mm x 400 mm, with a repeatability of \u00b10.015 mm.<\/p>\n