Introduction The current mainstream production process of power batteries, whether it is the cylindrical route led by Tesla and Panasonic, or the square route led by Samsung and CATL, still uses the winding manufacturing process in the digital lithium battery era.

Foreword

The current mainstream production process of power batteries , whether it is the cylindrical route led by Tesla and Panasonic , or the square route led by Samsung and CATL, is still using the winding manufacturing process in the digital lithium battery era. However, with the trend of automotive-grade power batteries requiring large capacity, large scale, and standardization, the requirements for manufacturing consistency, manufacturing quality, and manufacturing safety are also getting higher and higher, and problems in the winding process have gradually emerged.

In this context, the lamination process can well meet the demand for uniform and parallel movement of lithium ions inside the battery. The lamination process has comprehensive characteristics such as uniform contact interface, low internal resistance, high energy density, good rate characteristics, and uniform expansion and deformation of the pole pieces. It has become an important trend in the development of battery structures in the future.

Classification of lamination equipment

Z-type lamination can be divided into single-station Z-type lamination machine, multi-station Z-type lamination machine, swing-type Z-type lamination machine and die-cutting Z-type lamination machine. Analyzing from the perspective of cell structure and process, since the mechanism of Z-shaped stacking is the reciprocating high-speed movement of the diaphragm material coupled with the pressing action of the stacking platform, this process will inevitably lead to inaccurate positioning of the pole pieces (the pressing needle moves away from the pole pieces and cannot be monitored online), and the online data cannot be closed loop. At the same time, the separator will have uneven stretching and deformation, and the risk of deformation and damage during high-acceleration movements will be higher.

From a manufacturing perspective, Z-shaped laminates require auxiliary time for blanking and tail rolling, which will have a greater impact on efficiency during the battery manufacturing process. In addition to improving single-station efficiency, the Z-type lamination method generally adopts multi-station production methods to improve efficiency. However, the multi-station Z-type stacking machine has a relatively complex pole piece scheduling system, and the actual utilization rate of the whole machine is low.

Composite lamination can be divided into composite rolling machine, composite stacking machine and composite folding machine . The foundation of composite lamination requires the use of double-sided rubberized diaphragms, including water-based or oil-based diaphragms. The pole pieces and separators are adhered together through pressure and temperature to form a composite unit, and then different methods are used to shape the battery core. At the same time, composite lamination technology is more suitable for the production of future semi-solid or all-solid-state batteries. Composite laminates can ensure that the separator tension is uniform without sudden changes in stretch. The separator pole pieces have a uniform interface, and the positive and negative pole pieces can be detected online. The alignment of the separators enables a closed loop of manufacturing data, which is very helpful for improving the quality of laminate manufacturing.

Lamination classification and advantages and disadvantages

Principle of lamination equipment

① Z-type lamination machine: This equipment completes the automatic lamination, gluing and automatic blanking functions of power batteries. The diaphragm is automatically unrolled, passes through the transition roller, and is introduced into the main lamination table by the vertical tension mechanism. The main stacking table drives the diaphragm to reciprocate forward and backward, fold it in a Z-shape and place the pole piece. The positive and negative manipulators take out the pole pieces from the positive and negative pole piece boxes respectively, position them on the secondary positioning table, and accurately stack them on the main stacking table. After stacking to the set number of pieces, the stacking will stop. After the tail rolling and gluing are completed, the material will be automatically transferred to the subsequent process. The equipment flow chart and main performance index table are as follows:

Z type lamination machine equipment flow chart

Z type lamination machine main performance index table

② Composite lamination machine: is used to realize high-speed and fully automatic lamination process, which mainly includes positive and negative electrode plates and separator unwinding mechanism, electrode plate cutting and dust removal mechanism, electrode plate and separator thermal compounding mechanism, lamination platform, battery core hot pressing, glue application, weighing, QR code affixing and scanning mechanism, etc.The equipment flow chart and main performance index table are as follows:

composite lamination machine equipment flow chart

composite lamination machine main performance index table

h The key structure of tml1 lamination equipment

① Z-type lamination machine, main components include: frame system, positive/negative electrode cassette assembly, separator unwinding assembly, negative electrode sheet secondary positioning assembly, stacking table assembly, manipulator assembly, diaphragm cutting assembly, cell glue assembly, cell blanking assembly. Schematic diagram of

Z type lamination and gluing

② composite lamination machine, the main components of include: rack system, placement Roll system, tension control system , pole piece defect detection, Mylar film rewinding and unwinding system, correction system, pole piece cutting/feeding system, thermal compounding system, lamination platform, glue application mechanism, Hi-pot testing mechanism, weighing mechanism, QR code scanning mechanism, unloading mechanism, dust control mechanism.

Schematic diagram of composite lamination gluing

Development trend of lamination equipment

♦ Single machine efficiency improvement: has gradually increased its capacity from 1GWh of a single machine to 2GWh, 4GWh, and 8GWh.

♦ product qualification rate has been improved: has gradually developed from the existing 99% to 99.5%, 99.9%, and 99.99%. At the same time, the consistency CPK of the product has gradually increased from 1.33 to more than 2.0.

♦ device stability improvement: MTBF has been gradually developed to thousands of hours.

♦ intelligent integration: die-cutting and lamination integration, data closed-loop intelligence.

The core indicator roadmap of stacking machine equipment is as follows:

The core indicator roadmap of stacking machine equipment

Conclusion

Although the lamination process has obvious advantages in improving the performance of power batteries, the practical problem facing industrial chain companies is that the lamination process faces problems such as burrs and dust control in actual industrial applications, and continuous breakthroughs and innovations are still needed in the future development of manufacturing technology.