How does a laser welding machine for supercapacitor maintain safe sealing under the trends of fast charging and high energy density?
Publish Time: 2025-12-30
With the extreme pursuit of range and charging speed in electric vehicles and energy storage systems, cylindrical lithium-ion batteries are rapidly developing towards higher energy density and ultra-fast charging capabilities. However, increased energy density means more active materials, a higher voltage platform, and a greater risk of heat generation; fast charging brings about drastic lithium-ion migration and localized overheating. Against this backdrop, the safe sealing of the battery casing becomes a crucial barrier to prevent electrolyte leakage, isolate external moisture intrusion, and suppress the spread of thermal runaway. The core of achieving this sealing is the highly precise laser welding process. The laser welding machine for supercapacitor, through multi-process collaboration, high-precision control, and intelligent feedback, ensures that every battery remains completely leak-proof even under harsh operating conditions.
1. Multi-stage welding process: Constructing a fully enclosed safe cavity
The sealing of a cylindrical battery is not a single weld point, but a complete sealing system composed of current collector welding, cover plate welding, casing sealing welding, and injection port sealing pin welding.
The current collector welding reliably connects the electrode tab to the current collector plate, ensuring a low-impedance path under high-current fast charging and preventing welding failure caused by localized overheating.
The cover plate and current collector are pre-assembled and then welded together to form an upper cover assembly integrating current conduction and a safety valve. The most critical step is the shell sealing weld, which uses a circular or spiral trajectory to fuse the cover plate to the steel shell, forming a vacuum-sealed cavity with high airtightness.
Finally, the sealing needle welding seals the injection hole, completing the final seal.
Each process is interconnected; even a minor defect in any step can compromise the overall seal. The laser welding machine for supercapacitor, through its modular workstation design, ensures that the output of the preceding process precisely matches the assembly tolerances of the subsequent process, eliminating incomplete welds or cracks caused by misalignment.
2. High-precision alignment and process control: Eliminating the source of sealing failure
Before the cover plate and shell sealing weld, the system automatically identifies the concentricity of the cover plate and shell opening using a high-resolution vision positioning system, controlling the error within ±0.02mm. Subsequently, the laser head dynamically adjusts the beam path based on real-time coordinates to ensure a uniform and continuous weld. During welding, closed-loop power monitoring and plasma monitoring technology are employed to capture the molten pool status in real time—if spatter, porosity, or incomplete fusion occurs, the system immediately alarms and rejects defective products. Especially in large-size batteries such as the 4680, the welding trajectory often employs an optimized spiral + filler scanning pattern, ensuring deep penetration while avoiding heat accumulation that could lead to casing deformation.
3. Material Adaptation and Process Optimization: Addressing the Challenges of High-Energy Systems
High-energy material systems such as high-nickel cathodes and silicon-carbon anodes are extremely sensitive to moisture and oxygen, requiring the welding area to be free of oxidation, contamination, and microcracks. The laser welding machine for supercapacitor employs the following measures to ensure safety:
An inert gas protective shield is used to create positive pressure protection in the welding area, preventing metal oxidation at high temperatures;
For copper-aluminum dissimilar metal connections, green or blue lasers are used to increase absorption, reduce heat input, and avoid the formation of brittle intermetallic compounds;
For welding nickel-plated steel shells and stainless steel cover plates, pulse waveforms and defocusing are optimized to control the width of the heat-affected zone and prevent shell softening during annealing.
4. Full-process traceability and intelligent quality inspection
The laser welding machine for supercapacitor integrates a MES system, where the welding parameters for each battery are recorded and bound to a unique ID. Simultaneously, post-weld sealing is checked through 3D visual inspection or helium mass spectrometry leak detection, ensuring the finished product's airtightness meets IP68 or even higher standards. This "controllable process, traceable results" quality system is the cornerstone of large-scale production of high-safety batteries.
Under the dual pressures of fast charging and high energy density, the safety boundaries of cylindrical batteries are increasingly tightening. The laser welding machine for supercapacitor, serving as the "last line of defense," has evolved from a simple connecting tool into a high-end piece of equipment integrating precision manufacturing, intelligent sensing, and a closed-loop quality system. With micron-level welds, it safeguards the safety baseline for millions of charge-discharge cycles—this is not only a victory for technology but also a solemn commitment to the lives and trust of users.
