Contract no.: 30N/12.01.2023
Project title: „Dezvoltarea de soluții inovatoare și tehnologii de fabricație avansată cu laseri, plasmă și radiații pentru rezolvarea problemelor societale„
Phase 20/2026 „Sudarea laser a unui cuplu nou de materiale eterogene cu conductivitate ridicata pentru contacte de baterii (PL2.14)„
Phase coordinator: Dr. Andrei Popescu
The term of the conclusion of the phase: 03.03.2026
Abstract:
Electrical interconnections in lithium-ion batteries for electric vehicles and other applications must ensure reliable operation over service lifetimes exceeding 10 years, which requires joints with low and stable electrical resistance, reduced heat input, and compatibility with mass production. This study defines interdisciplinary evaluation criteria (electrical/thermal, metallurgical, mechanical, and economic) and selects the Cu–Al material pair for manufacturing the contacts (tabs), considering its compatibility with conventional cell architectures and overall battery performance. Laser welding experiments were performed using a continuous-wave Yb:YAG source (λ = 1030 nm, P_max = 3 kW) integrated into a five-degree-of-freedom CNC system equipped with galvanometric scanner optics, enabling scanning speeds on the order of several hundred mm/s. Given the small material thicknesses (100–400 µm) and their susceptibility to deformation, maintaining rigid contact between the surfaces was treated as a critical prerequisite, since gaps exceeding 100 µm lead to lack of bonding and increase the risk of vaporization/perforation. Accordingly, clamping solutions were analyzed, and individual pressing of each tab was identified as the optimal approach to increase flexibility and productivity, with high automation potential. Process parameters were optimized for both dissimilar and similar joints on a CuNi backing plate (2 mm), using a parallel-line scanning strategy (0.25 mm pitch), a ~42 µm spot size, and a 10° inclination angle, without shielding gas. The resulting regimes included, for Al (0.4 mm)/CuNi (2 mm), P ≈ 650 W and v ≈ 250 mm/s (penetration depth 150–200 µm), and for CuNi (0.2 mm)/CuNi (2 mm), P ≈ 800 W and v ≈ 420 mm/s (penetration depth 80–100 µm). Electrical validation of the joints on a batch of three batteries indicated internal resistances in the range of 0,63–0,72 mΩ, below the 1 mΩ threshold, confirming compliance with application requirements and the potential for industrial implementation of the process.
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