The handling of chemical compounds to create a battery cell requires specialized equipment to transfer the chemical media, which comes in the form of a fluid or a powder. The chemicals handled are usually abrasive, corrosive, or shear sensitive. Special considerations must be taken when choosing the equipment that can endure such compositions.
It is critical that non-conductive wetted parts are used in cathode production. Conductive/metallic parts that come into contact with the cathode slurry will pose a threat for contamination and can affect the quality of the lithium-ion battery cell. For this reason, makers of peristaltic pumps used in the process must meet the strict requirements of lithium-ion battery manufacturing by not using copper, zinc or nickel in the components of their pumps.
A plant will implement specialized lithium-ion or solid state battery manufacturing pumps to carry out the majority of chemical media transfer used in the following processes integral to the manufacturing of battery cells.
Precursor Material for Cathode
Cobalt and nickel are raw materials used in the production of precursor materials for cathodes in Li-ion batteries, while sulfide ionic conductors such as lithium argyrodite are used in SSBs. To create the precursor material for a cathode, the following process stages are used:
- Pre-processing – salt dissolution and proportion, where ammonia is used as an ion complexant
- Reaction – aqueous alkali and complexant are added to a vessel, where they react to combine into ternary precursor grains
- Post-processing - after the grain reaches a set size, the slurry is filtered, washed and dried, to attain the ternary precursor
These processes require that the integrity of the product is carefully maintained by utilizing reliable and low-shear pumping equipment that provides accurate proportioning, dosing and/or metering. Most Albin Pump hose pumps applications occur during the cathode manufacturing stage of battery manufacturing. A list of these applications can be seen after the separator film/electrode coating section.
Anode Graphitization
Graphitization is the process of exposing raw materials to extremely high heat (2500 to 3300 K) for a prolonged period of time to create natural or synthetic graphite used to manufacture anodes. In addition, the graphite is purified with hydrofluoric, hydrochloric, and sulfuric acids.
Specialized pumps are required during anode graphitization to transfer acidic slurry, to filter acids and impurities and for wastewater treatment.
Separator Film Manufacture and Electrode Coating
Separator film is a permeable membrane that is placed between a battery’s anode and cathode. The film prevents the electrodes from coming in contact but allows for free movement of ions between them. They act as insulators but can conduct ions.
Electrode coating achieves the same result, except it uses a specially formulated slurry. This is a mix of solid conductive particles along with active materials, polymer binders and a solvent medium. The electrode is coated with the slurry and then dried.
Separator film is created using a specialized plastic extrusion method that creates long rolls of the film, while in electrode coating, the slurry is “tape casted” on current collectors.
