In recent years, the battery technology for electric vehicles has developed rapidly, and the driving range has become an important indicator to measure the performance of electric vehicles. The large-capacity lithium-ion battery system has become the key to improving this indicator. Lithium-ion battery system required for vehicle working voltage and driving range. The connection between the cell and the cell generally adopts the welding method of the connection row. In the module manufacturing process, the general soft-packed cell module adopts laser welding.

The welding methods applied to the connection of power battery modules mainly include:

1. Resistance welding

Resistance welding is a type of welding method that uses resistance heat as energy. Resistance welding uses the resistance heat effect generated by the current flowing through the contact surface and adjacent areas of the workpiece to heat it to a molten or plastic state, and at the same time pressurize it to form a metal bond. method of welding.

In the grouping process of power batteries, resistance welding, as a relatively mature process, is used in the welding of power battery cells and busbars, and the connection of power battery tabs and parallel conductive bars. Due to the simple equipment and low cost, in the early stage of the development of the power battery industry, there were many applications, and in recent years, it has been gradually replaced by more advanced laser welding.

2. Laser welding

Laser welding has high efficiency and is easy to realize automated production. After the continuous improvement of the welding process and the limitation of the thermal influence in the molding process, the application in actual production is also increasing. Laser welding and industrial robots are gradually becoming the main force of the automatic power battery module production line.

Laser welding is a high-efficiency and precise welding method that uses a high-energy-density laser beam as a heat source. Laser welding is mainly used for welding thin-walled materials and low-speed welding.

The laser welding process is of heat conduction type, that is, laser radiation heats the surface of the workpiece, and the surface heat passes through. The heat conduction diffuses to the inside, and the workpiece is melted to form a specific molten pool by controlling parameters such as the width, energy, peak power and repetition frequency of the laser pulse.

Laser welding process of battery module

1. A method for forming through-holes by compounding multiple layers of materials, wherein one layer of material is a connecting layer of a connecting piece and a column, and a multilayer material stack that ensures welding performance is used to ensure the conductivity of the connecting pad.

2. The base material of the connection sheet is formed by laminating multiple layers of foil to form a flexible area to compensate for the displacement caused by the expansion of the battery cells.

When the welding quality of the two materials cannot be satisfied, different substitute materials are used, and sophisticated structures or technologies are further utilized to make up for the performance loss of the exchange material.

New energy power lithium battery module welding is a very critical part of the new energy battery module assembly process. The quality of the welding will directly affect the product quality, so the laser welding machine is particularly important in the power battery module welding process.