Date: 2023-12-15 hits: 296
At present, the lamination technology route of lithium-ion batteries is mainly divided into four categories: cutting and lamination, Z-shaped lamination, thermal composite lamination and roll lamination. Among them, Z-shaped lamination and cutting lamination are essentially Z-shaped lamination, which is also a more widely used lamination process in China; The biggest feature of the thermal composite lamination is to realize the complete slicing of the positive electrode, the negative electrode and the diaphragm at one time, which effectively improves the quality and production rate of the lamination and the cell, and is relatively more difficult.
1. Cutting and Folding Technology
Cutting and stacking technology is still essentially Z-type stacking technology, as an improvement of Z-type stacking technology, it has gradually become a development trend, and its advantages are to improve the yield and stacking efficiency.1, improve the yield: the battery is prone to damage in the transport process of different processes, and the multiple links are concentrated on a device, which can reduce the possibility of battery damage in the process. In the past, the traditional production method was to take slices from the material box and stack them. Bump and pole ear folding may occur in the process of taking pieces, and the cutting and folding machine integrates three types of pole die cutting/laser cutting, Z-shaped laminator and adhesive hot press, solving the problem of bending and suction, reducing bump and improving yield by reducing loading and unloading and transferring processes. 2, improve the stacking efficiency: the cutting and folding machine will be the positive and negative electrode sheet and diaphragm at the same time, under the action of the main stacking table or pendulum, folding in a Z-shape, when stacked to the set number of pieces, the diaphragm cutting glue, and then hot pressing into the cell, such as the leading intelligent maximum stacking efficiency of 800PPM (0.075s/pcs), Li Yuanhang high-speed cutting and stacking machine stacking speed up to 800ppm0.15s/pcs (three stations).
2. Z-type Laminated Technology
Z-type lamination technology is a common lamination process at present, by pulling the diaphragm between the lamination platform to move back and forth, to achieve the cross stacking of positive and negative electrodes.The problem with Z-lamination technology is that the diaphragm is easily deformed and the stacking efficiency is not high. 1, the diaphragm is easy to deform: the diaphragm of Z-type lamination technology will swing around with the movable lamination table, and the pendulum shaft of the diaphragm is easy to cause asymmetry, resulting in inconsistent diaphragm deformation; The diaphragm tension is from zero to maximum each time, resulting in inconsistent membrane stretching and deformation, while the porosity, average pore size and specific surface area of the diaphragm will have a greater change, affecting the quality of the cell. 2, stacking efficiency is not high: in the stacking process, it is necessary to swing the diaphragm to stack the pole sheet and avoid the diaphragm alternately, increasing the time required for single stacking, and only single stacking can be achieved, the stacking efficiency is difficult to have a large improvement, generally 0.5s/pcs/ station, if the number of battery pole layers is 30 layers, the time to complete a battery is 15 seconds. Four batteries can be completed in one minute, that is, the efficiency is only 4PPM.
3. Thermal Composite Lamination Technology
The working principle of the thermal laminating machine is that the positive coil, the negative coil and the diaphragm feed at the same time. Before entering the heating device, the positive sheet and the negative sheet are cut into a single pole sheet of the required size by the cutting knife. The combination of the positive sheet, the negative sheet and the diaphragm enters the heating system under the action of the roller. After heating, the diaphragm is cut off to form a single laminating unit, and then the single laminating unit is stacked together by a mechanical device, and then the stack is hot pressed to form the pole core. The diaphragm of the thermal composite machine is coated with glue, which is sticky when heated. After baking, the positive and negative electrode plates are thermally combined with the diaphragm, and then cut into composite units by rolling. Then a manipulator transfers it to the lamination table for lamination. After stacking, hot press, and then glue.Thermal laminating machine pole plate and diaphragm simultaneously rewind, can avoid Z-shaped laminating diaphragm deformation and other problems. In the thermal composite laminating process, the tension direction of the diaphragm and the pole sheet is always unchanged, and the speed remains uniform. Compared with the constant change of tension during the winding process and the periodic change and swing of the tension of the Z-type laminating machine, the thermal composite laminating machine has continuous single-direction transmission, stable speed and tension control in the production process, and the pole-core interface is flat. The mechanical properties of the diaphragm, porosity, average pore size, the interface between the pole plate and the diaphragm are uniform, and the quality of the cell is higher. The technical difficulty of thermal composite lamination is higher than that of Z-lamination, which is suitable for high energy density and large cell. Compared with Z-type laminated multi-thermal laminated and roll pressing processes, the technical difficulty is higher, and the post-injection process is more difficult. Thermal laminating machine integrates production, laminating and hot pressing at the same time, with high efficiency, energy saving and space saving, and is more suitable for high energy density and large cell.
4. Roll-In-One Technology
LG has the patent of Stack & Folding, not for sale, and the equipment manufacturer is MANZ, Germany. The process is generally to first cut the positive and negative electrode pieces into units, and paste them on the diaphragm through the setting of the turntable and the lifting sucker. Then the pole sheet is wrapped separately in the way of winding to realize two groups of positive and negative pole sheets overlapping with each other, with high speed and efficiency.According to the LG New Energy website, LG's Stack & Folding patent will stack a positive electrode, a negative electrode and a diaphragm to form a Bi-cell, and then fold multiple bi-cells to form a battery. Between the positive and negative plates, LG Neenergy also utilizes its proprietary Safety Reinforced Separator (SRS) diaphragm, which is coated with ceramic and heated to increase mechanical strength, thereby preventing internal short circuits, greatly improving battery safety and performance.
