In the production and assembly of batteries—whether cylindrical lithium-ion batteries, prismatic power batteries, or soft-pack energy storage batteries—welding is a critical process that directly affects battery safety, energy density, and service life. Battery welding requires precise connection of tabs, busbars, and casing components while minimizing damage to heat-sensitive battery cells. Among various welding equipment, laser welding machines have emerged as the optimal solution for battery manufacturing due to their unique technical advantages, outperforming spot welding machines, ultrasonic welding machines, and other traditional devices. This article focuses on the battery welding scenario to analyze the core comparative advantages of laser welding machines.
Battery welding has strict requirements for temperature control, welding precision, and joint strength. Traditional welding equipment often struggles to meet these demands, leading to potential quality risks:
- Spot welding machines: Rely on resistance heating to form solder joints, but the heat input is difficult to control. Excessive temperature can damage battery diaphragms and electrolytes, causing safety hazards such as short circuits. The large solder joint size affects the layout density of battery packs, reducing energy density. Additionally, electrode wear during long-term use leads to inconsistent solder joint quality, increasing the rework rate of battery packs.
- Ultrasonic welding machines: Suitable for thin material welding such as soft-pack battery tabs, but their welding strength is limited. They cannot handle thick busbars or casing welding in power battery packs. Moreover, ultrasonic welding is sensitive to material surface cleanliness—any oil or oxide layer can cause virtual welding, which is difficult to detect in subsequent inspections and may lead to battery failure during use.
- Argon arc welding machines: Generate a wide heat-affected zone during welding, resulting in obvious deformation of battery casings and tabs. The slow welding speed makes them unsuitable for mass production of battery packs. Additionally, the arc radiation and spatter during welding can contaminate battery components, affecting overall performance.
These limitations make traditional welding equipment increasingly inadequate in the context of high-precision, high-efficiency battery manufacturing.
Laser welding machines use focused high-energy laser beams to achieve localized, rapid heating of battery components. Compared with traditional equipment, they offer targeted advantages for battery welding:
Battery cells are highly sensitive to temperature—excessive heat can cause electrolyte decomposition or diaphragm melting. Laser welding machines deliver concentrated energy, with a heat-affected zone as small as 0.1–0.3mm, far narrower than the 2–5mm zone of spot welding machines. This minimizes thermal damage to battery cells while ensuring stable connection of tabs and busbars. For example, in the welding of 18650/21700 cylindrical battery packs, laser welding can accurately target the nickel strip-battery pole connection without affecting the internal structure of the cell, reducing the risk of thermal runaway.
Modern battery packs pursue high energy density, requiring compact layout of cells and components. The focused spot of laser welding machines can be adjusted to 0.05–0.2mm, enabling precise welding of micro-tabs and narrow busbars. Compared with spot welding machines’ millimeter-level solder joints, laser welding reduces the occupied space of connections, allowing more cells to be arranged in the same volume. This advantage is particularly prominent in portable electronic device batteries and new energy vehicle power battery packs, directly improving product endurance performance.
Battery packs are subject to vibration, impact, and temperature changes during use, requiring welding joints with high tensile strength and corrosion resistance. Laser welding forms dense, defect-free weld seams with shear strength 30–50% higher than that of ultrasonic welding and 20–30% higher than spot welding. For prismatic battery casing welding, laser welding achieves seamless sealing, preventing electrolyte leakage and improving the battery’s service life. In contrast, spot welding’s discrete solder joints are prone to stress concentration and fatigue failure under long-term use.
Battery manufacturing involves various materials such as copper, aluminum, nickel, and their alloys. Traditional equipment struggles with dissimilar material welding—for example, spot welding of copper-aluminum tabs often results in brittle intermetallic compounds and poor conductivity. Laser welding adjusts parameters such as energy density and welding speed to control the melting ratio of dissimilar materials, forming high-quality joints with low contact resistance. It also handles thick busbars (2–5mm) and thin tabs (0.1–0.3mm) equally well, adapting to different welding needs in battery packs, from tab connection to casing sealing.
Battery manufacturing is highly automated and mass-produced, requiring welding equipment to keep up with production line beats. Laser welding machines achieve a welding speed of 1–3m/min, 2–3 times faster than spot welding machines. When combined with six-axis robots or gantry motion systems, they can complete thousands of solder joints in a single battery pack with consistent quality, avoiding human error in manual operation. For example, in new energy vehicle battery pack production lines, laser welding stations achieve a cycle time of 30–60 seconds per pack, meeting the demand for 10,000+ units of daily output—an efficiency that traditional welding equipment cannot match.
Battery safety is regulated by strict industry standards, requiring traceable and consistent welding quality. Laser welding machines are equipped with digital control systems that record welding parameters (power, speed, spot size) in real time, enabling full-process traceability of each battery pack. Unlike spot welding machines with electrode wear issues, laser welding has no consumable wear, ensuring consistent solder joint quality across batches. This stability helps enterprises pass international certifications such as IEC and UL, enhancing product market competitiveness.
Laser welding machines have become the standard equipment in key battery manufacturing links:
- In consumer electronics, laser welding is used for micro-tab welding of smartphone and laptop batteries, ensuring compact size and reliable connection.
- In new energy vehicles, power battery packs (such as ternary lithium and lithium iron phosphate battery modules) adopt laser welding for busbar connection and casing sealing, improving battery safety and endurance.
- In energy storage batteries, laser welding handles large-size battery module welding, withstanding long-term high-current charging and discharging without joint failure.
In battery welding scenarios, laser welding machines outperform traditional equipment such as spot welding and ultrasonic welding in temperature control, precision, joint strength, material adaptability, efficiency, and quality stability. These advantages directly address the core demands of battery manufacturing—safety, high energy density, and reliability—making laser welding an indispensable technology for the development of the new energy battery industry. As battery technology advances toward higher energy density and smaller sizes, laser welding machines will continue to iterate, bringing more efficient and precise solutions to battery manufacturing.
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