In the manufacturing of power batteries, energy storage batteries, and other equipment, assembling multiple cells into battery modules is a core step in achieving the required voltage and capacity. This process requires the orderly series and parallel connection of individual cells using specific connection methods. The reliability and consistency of these connections directly determine the performance and safety of the module, making the selection of connecting pieces and the welding process particularly critical.
Commonly used connecting pieces for battery modules are made of copper or aluminum, with a thickness controlled between 0.3-1mm. This ensures smooth current transmission while also meeting the requirements for lightweight structure. The connecting pieces need to be precisely aligned with the cell electrodes—the top of the steel casing of cylindrical batteries or the terminals of prismatic batteries. Through series and parallel connections, voltage superposition and capacity aggregation are achieved. For example, series connection increases the total voltage, while parallel connection increases the total capacity, thus matching the power requirements of different devices.
Among various connection processes, ultrasonic welding has become the mainstream choice in the industry due to its significant advantages. Its most prominent feature is its extremely high welding efficiency, with a single weld point requiring only 0.1-0.5 seconds. This significantly improves the cycle time of module production lines, meeting the demands of large-scale manufacturing. Simultaneously, ultrasonic welding produces excellent weld point consistency, with resistance deviation controlled within 10%. This characteristic effectively avoids the "weakest link" effect in battery cells. Because the conductivity of each weld point is uniform, uneven local connections prevent individual cells from experiencing overcharging or discharging stress, thus extending the overall cycle life of the module.
Compared to traditional connection methods, the low-heat characteristic of ultrasonic welding is crucial for ensuring module safety. While screw connections are simple to operate, their high contact resistance can lead to loosening due to overheating over time, posing a safety hazard. Laser welding generates high temperatures, potentially damaging the sealing structure of the battery cell casing and causing electrolyte leakage. Ultrasonic welding, on the other hand, achieves metallurgical bonding between metals through high-frequency vibration. The heat generated during the welding process is extremely low, ensuring connection strength while avoiding damage to the battery cells, fundamentally improving the safety and stability of the module.
Ultrasonic welding, with its advantages of high efficiency, precision, and low damage, has become an ideal solution for connecting battery cells in series and parallel. It not only solves many pain points of traditional connection methods but also provides a reliable guarantee for the large-scale production of battery modules, driving the development of new energy equipment towards a safer and more efficient direction.
