Battery sludge is very viscous, contains raw materials which must be deagglomerated and requires reproducible mixing.
– Fabio Boccola, CEO of Hauschild Engineering
DETROIT / HAMM, MICHIGAN, USA / GERMANY, Oct 27, 2021 /EINPresswire.com/ – The production of high quality battery sludge presents many challenges: it is very viscous, contains raw materials that must be deagglomerated and require high repeatability / reproducible mixing. Hauschild therefore presents its SpeedMixer®, which can be used to mix almost any viscosity, at the Battery Show Europe conference. The power of these centrifugal mixers is so high that the particles are reliably deagglomerated and air bubbles and voids are eliminated. Automated programs ensure repeatability.
The development of high-performance batteries is crucial to enable the efficient use of renewable energy sources and to advance the electrification of vehicles, for example. All of these developments are undoubtedly based on breakthroughs in materials. Optimization of the anode material is therefore an important area of research, and proper mixing is an essential part of the process.
For batteries, the anode and cathode are usually made by mixing an active material (graphite), binder powder, solvents and additives (the keyword is “slurry mixture”). This slurry is then pumped into a coating machine, which applies the slurry mixed with the aluminum foil for the cathode and the copper foil for the anode.
Challenge of mixing anodes
Anodes have a variety of compositions for different applications. The most common materials for anodes are carbon / graphite as an active anode powder, carboxymethylcellulose (CMC) as a binder / film former, as well as conductive materials and additives, and deionized water as than solvent. The mixture of these components then depends on a lot of know-how and experience. Fabio Boccola, CEO of Hauschild Engineering, reveals the procedure necessary for the result of the mixture to be convincing. “First of all, the binder is dispersed into the other powders by dry mixing. CMC tends to clump when added directly to water. Therefore, we recommend using our Hauschild SpeedMixer.® to first dry mix the CMC powder with the carbon / graphite powder for about 30 seconds at medium speed. This disperses it and prevents clumping when added to water. The viscosity / solids content can also be adjusted to desired values in the final step. In addition, we recommend that you use a mixing container with a lid that has a small hole in the center to prevent pressure build-up. Vacuum mixing removes voids / bubbles, dissolved gases and gases adsorbed on the charges / powder. “
Mixing cathodes and separating sheet
The active cathode materials are the main elements that determine the compositional differences in the manufacture of positive electrodes for battery cells. Cathode materials consist of cobalt, nickel, and manganese, which form a multimetallic oxide material in their crystal structure to which lithium is added. Material optimization and testing becomes more and more important for the further development of battery technology, as the demand for more powerful batteries continues to increase.
Fabio Boccola explains: “Dissolving polyvinylidene fluoride (PVDF) binder in N-methyl-2-pyrrolidone (NMP) solvent can take hours and time in conventional equipment. It is common for laboratories to pre-dissolve a concentrate to save time in each formulation Preparation of a concentrate in a SpeedMixer Hauschild®, on the other hand, is usually done in less than ten minutes. “
In addition to the cathode and anode mixture, the required separator film between cathode and anode can also be produced quickly and safely. The separator, which – as the name suggests – physically separates the anode and the cathode, is a microporous compound usually based on plastics such as polypropylene or polyethylene.
While the material itself is much easier to mix than the much more viscous components of the cathode and anode, the challenge of mixing the separator is the required homogeneity. Voids in the final mix should be minimized to create more lithium storage sites.
The secret of success: the use of centrifugal forces
DAC stands for Asymmetric Double Centrifuge. The particularity of this mixing principle is the double rotation of the mixing cup. The combination of centrifugal forces acting in different planes allows an extremely efficient mixing process characterized by a homogeneous result – without the use of agitators. Almost 100 percent degassing is already achieved during the mixing process, eliminating even the smallest microbubbles. An additional degassing cycle is not necessary. Mixing units with vacuum technology are available for complete degassing. Programmable cycles ensure absolutely identical and reproducible mixing of each batch and result in a significant acceleration of the development process.
Fabio Boccola says: “In the R&D laboratories, Hauschild SpeedMixer® are essential equipment. They are fast, highly efficient, dust free, no additional cleaning is required and there is less impact on employees and the environment. Thanks to its extremely fast mixing, the Hauschild SpeedMixer® dramatically shortens the process of product development, analysis and quality assurance in laboratories. The world needs better batteries – and we are proud to be involved in many new innovations ”.
More info: www.hauschild-speedmixer.com
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Hauschild SpeedMixer® can be used to mix almost any viscosity, for example plasticine