One Of The Ten Key Equipment For Lithium Batteries: Pulping Equipment-xmacey.com

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One Of The Ten Key Equipment For Lithium Batteries: Pulping Equipment

September 06 , 2024

One Of The Ten Key Equipment For Lithium Batteries: Pulping Equipment

What is pulping

Pulping is the active substance, conductive agent, dispersant, binder, additives and other components in accordance with a certain proportion and order into the mixer, in the stirring paddle and dispersion disc turning, kneading, shear and other mechanical action mixed in the 1 period, the formation of uniform and stable solid-liquid suspension system.

Introduction of pulping process

1.The importance of the pulping process

The upper limit of the performance of lithium-ion batteries is determined by the chemical system used (positive active material, negative active material, electrolyte), and the actual performance depends on the microstructure of the pole piece. The microstructure of the pole piece is mainly determined by the microstructure of the slurry and the coating process, which is dominated by the microstructure of the slurry. Therefore, there is a widely recognized statement that in the impact of the manufacturing process on the performance of lithium-ion batteries, the impact of the previous process accounts for at least 70%, while the impact of the pulping process in the previous process accounts for at least 70%, that is, the impact of the pulping process accounts for about half.

2.The composition of the slurry and the ideal dispersion state of each component
The electrode materials of lithium ion battery include three main components: active material, conductive agent and binder, in which the active material accounts for the vast majority of the total weight, generally between 90% and 98%, and the proportion of conductive agent and binder is relatively small, generally between 1% and 5%. The physical properties and sizes of these main components vary greatly, among which the particles of active substances are generally between 1 and 20μm, while most of the conductive agents are nano-carbon materials. For example, the primary particle diameter of commonly used carbon black is only tens of nanometers, the diameter of carbon nanotubes is generally below 30nm, and the binder is a polymer material, which is soluble in solvents and forms microemulsions in solvents. The electrode of the lithium-ion battery needs to achieve good electron transport and ion transport, so that the distribution state of the active material, the conductive agent and the binder in the electrode is required to meet certain requirements.

The electrodes of lithium-ion batteries need to achieve good electron and ion transmission, which requires that the distribution state of active materials, conductive agents and binders in the electrodes meet certain requirements. The ideal distribution state of each material in the electrode is shown in Figure 1, that is, the active material is fully dispersed, the conductive agent is fully dispersed and in full contact with the active material to form a good electronic conductive network, and the binder is evenly distributed in the electrode and bonds the active material and the conductive agent to make the electrode a whole.

Figure 1-Ideal distribution of materials in lithium-ion battery electrodes

In order to obtain the microstructure of the pole piece that meets the above requirements, it is necessary to obtain a slurry with a corresponding microstructure in the pulping process. That is, the active material, the conductive agent and the binder in the slurry must be fully dispersed, and good bonding between the conductive agent and the active material, and between the binder and the conductive agent/active material must be formed, and the dispersion state of each component in the slurry must be stable.

Dispersing equipment and process of slurry
The equipment used for slurry dispersion mainly includes two categories. One is the equipment that uses the shear force generated by fluid motion to disperse the particle aggregates, including slurry mixing equipment and kneaders using various types of stirring paddles, and also includes three-axis mills and disc mills. The other is the equipment that uses grinding beads to impact the particle aggregates to achieve the dispersion effect, mainly including stirring mills. Of course, there are some more special dispersion equipment, such as ultrasonic dispersion machine is the use of ultrasonic cavitation and instantaneous micro-jet to the particle aggregates for dispersion.

The above dispersion equipment is not all suitable for lithium ion battery pulping. For example, the stirring mill using grinding beads is easy to damage the coating layer on the surface of some positive and negative active materials due to the large impact force generated by grinding beads, and even may break the active materials, so it is rarely used for lithium ion battery pulping. Ultrasonic dispersion equipment is not suitable for high solid content and high viscosity slurry, the slurry of lithium ion battery is precisely high solid content (positive electrode slurry can reach 60% ~ 80%, negative electrode slurry can reach 40% ~ 60%) and high viscosity (20~200Pa · s), which is not suitable for ultrasonic dispersing machine to disperse. Therefore, in fact, the equipment used for lithium-ion battery pulping belongs to the type of dispersing by the shear force generated by the movement of the fluid, including the mixer, the kneader, etc, the most typical equipment is the double planetary mixer.

Double planetary mixer

The working principle of the double planetary mixer is to use 2~3 slow mixing paddles to do a combination of revolution and autobiography, so that the trajectory of the blade can cover the entire space inside the mixing barrel.

Double planetary mixer motion trajectory

The trajectory of the slow blade of a double planetary mixer when it combines revolution and rotation.

The outstanding advantage of the double planetary mixer is that it can easily adjust the feeding sequence, speed and time and other process parameters to adapt to different material characteristics, and can be easily reworked when the slurry characteristics do not meet the requirements, adaptability and flexibility Very strong. In addition, when the variety is switched, the cleaning of the double planetary mixer, especially the small mixer, is relatively simple.

Acey New Energy is specialized in researching and manufacturing of high-end equipment for lithium-ion batteries. We can not only provide production equipment for cylindrical cell, coin cell, and pouch cell lithium-ion batteries, but also provide one-stop solutions for lithium battery production line. If you are new to the lithium-ion battery industry and want to build your own lithium-ion battery production line or lithium-ion battery pack assembly line, we can provide you with professional technical support and guidance, please feel free to contact us!

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