Mixing is one of the basic operations in mechanical processing engineering. In this way, at least two starting substances are combined into one substance that should be as homogeneous as possible.
The mixing process is commonly followed by de-aeration since, during the processing of liquid to highly-viscous products, pockets of air or gas often cause problems. Pockets of air, hence oxygen, can have negative effects on the product – such as oxidation, rancidity of fats or oils, discoloration or deterioration of aroma and taste for example – and, for materials that are to be coated, can lead to porous and pitted surfaces. In contrast, de-aerated products are usually more chemically stabile and more durable.
The coating slurries for making the anode/cathode contain many different solid particles. Thorough mixing of these slurries is a major challenge in battery processing steps.
In other words, the state of the slurry components, which determines the physical properties of the slurry, plays an important role in the mixing and coating process to produce lithium-ion batteries.
Below are the tasks to be solved in the slurry mixing process.
Preparation of an appropriate atmosphere
Inserting and wetting of the particles
Dissolution of the binder
Realization of the appropriate energy for de-agglomeration
Temperature control during the process
Degassing of the solution
To make a LiBs cell, electrode slurry should be coat on the metal foil. Planetary mixer such as PMH is used to produce electrode slurry. Planetary Mixing and Kneading Machines are used when slurries with high viscosities especially thermo-sensitive components have to be processed.
In the mixing process, Planetary Mixing and Kneading Machines show their real potential for slurry that is very difficult to stir.
PMH is suitable for highly-viscous product and PML is solution for the product with medium viscosity. Therefore, In other words, because the viscosity of products suitable for the two mixers is different, the shape of the mixing tool of each mixer is different. The mixing elements carry out a rotating movement in a fixed vessel in addition to their self-rotation and thus run through the whole slurry.
Aggressive and abrasive media such as lithium are pumped safely and gently by positive displacement pumps. These pumps are used in almost all industry sectors for transporting and dosing difficult media, such as solids-bearing fluids having low to very high viscosities or even aggressive media which are used in battery production.
In battery production, the processes are also supported by pumping solution for all flow rates and pressures. For example, the NEMO® progressing cavity pumps, the TORNADO® rotary lobe pumps and the PERIPRO peristaltic pumps are used in vacuum defoaming, because slurries can be strongly suctioned even under high vacuum conditions and they are also pumping fluids in the stirring process: A variety of primary raw materials are pumped to the stirring tank and after being stirred at a high speed, the pumps will also transport them to the storage tank.
Especially, the progressing cavity pumps and the peristaltic pumps are used for applications in mixing process. Pumping liquids are Adhesive & glue, Conductive liquid & mixing slurry and Electrolyte, UV Resin or other.
In Mixing Process, the powder is mixed into the solvent. The mixture is called slurry.
It is important to understand the viscosity of the solvent or the slurry because it has different rheological properties depending on the content of them. Viscosity can be affected by the content of the powder, shear rate and shear stress. Slurry's viscosity can be measured by Rotational Rheometer (Kinexus Series).
You can also analyze Mass spectrometry or Gas chromatography with STA-QMS coupling system or the STA-GC-MS coupling system for component analysis of the solvent or the slurry.