Lithium battery Science Popularization Lithium battery manufacturing process (fr
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2023/07/30 11:35:01
The manufacturing process of lithium batteries consists of mixing the active substance, binder and conductive agent into a slurry and coating it on copper or aluminum collector to make a dry electrode pellet coating, which is compacted and densified, cut or slitted. The positive and negative electrodes and the diaphragm are assembled into a battery cell, injected into the electrolyte, and charged and discharged to activate the battery product.
According to the shape of the core can be divided into cylindrical, square and soft battery, its production process is slightly different. However, the overall process can be divided into three stages: the front process (electrode wafer manufacturing), the middle process (battery synthesis) and the rear process (formation and packaging).
The production goal of the production section of the previous process is to complete the production of positive and negative pole pieces. Its process route includes pulping, coating, roll pressing, slitting, making, die cutting, and related equipment such as mixer, coating machine, roll press, slitting machine, making machine, die cutting machine, etc.
pulping
Pulping is the process of mixing active material powder, binder, conductive agent and so on according to a certain proportion, and adding solvent to make a stable suspension.
Lithium battery slurry is divided into positive slurry and negative slurry, and its formula, dispersion uniformity, viscosity, adhesion, stability and consistency have an important impact on battery performance.
In the pulping process, the active substance, conductive carbon, thickener, binder, additive, solvent, etc. are put into the mixer in proportion to achieve a uniform solid-liquid suspension slurry through stirring to facilitate coating.
Wetting, dispersion and stability are important factors in the mixing process. The dispersion effect and bonding strength are affected by the type of stirring paddle, stirring speed, viscosity, vacuum degree and temperature.
High-quality stirring is the basis for the high-quality completion of the subsequent process, and will also directly or indirectly affect the safety performance and electrochemical performance of the battery.
Homogenizing equipment is divided into intermittent and continuous according to the operation mode, in which the double planet mixing homogenizer, the circulating homogenizer and the double spiral continuous grinding dispersion homogenizer are commonly used equipment.
coating
Coating is the positive or negative suspension slurry evenly coated on the surface of aluminum foil or copper foil, and then through the drying process to form a film.
In the coating process, the pump speed is adjusted according to the slurry parameters, and the coating thickness is controlled by adjusting the thickness and uniformity of the extrusion head gasket, so that the slurry is uniformly coated on the fluid collecting substrate. Then the solvent is removed by drying in the oven, so that the solid substance is bonded to the substrate, and the positive and negative electrode sheets are made.
The quality of the coating process will profoundly affect the consistency, safety and life cycle of the finished battery, so the coating machine is the most valuable equipment in the previous process.
Roll compression
Through the rolling process, the active substance can be in closer contact with the collector, thereby reducing the moving distance of electrons, reducing the thickness of the pole sheet, increasing the loading amount, and reducing the internal resistance of the battery to improve the conductivity. This can improve the volume utilization rate of the battery, and thus increase the capacity of the battery.
slitter
According to the process and the size of the incoming material, the film roll is cut into multiple rolls of the same size by the scuttling machine to meet the requirements of the cell size. In the slitting process, the pole slice is cut to the design width to meet the size requirements of the cell. In the process, the order of die cutting and scuttling is not necessarily, and even can be carried out at the same time.
die-cutting
The anode and cathode diaphragm is cut by forming knife die or laser to make the pole ear and the pole ear distance of specific shape and specification. The figure shows the state of the product after die cutting.
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