BINDERS & BINDER SOLUTIONS
Rotalab offers both Styrene-Butadiene Rubber (SBR) and Polyvinylidene Fluoride (PVDF) based binders, materials that are widely used in the lithium-ion battery manufacturing industry to hold the active material particles together and in contact with the current collectors i.e. aluminium foil (Al foil) or copper foil (Cu foil).
In the traditional Li-ion cell manufacturing process, PVDF (Polyvinylidene Fluoride) is mostly adopted in the cathode and anode slurry making processes. For processing requirements, cost and environmental issues, battery manufacturers are gradually moving away from using PVDF and instead making use of aqueous base materials.
An anode electrode is typically made by mixing active material (Graphite), binder powder, solvent and additives into a slurry, which is then pumped into a coating machine. The coating machine spreads the mixed slurry (paste) on both sides of the Al foil for the cathode and of the Cu foil for the anode. The coated foil is subsequently calendered to enhance the uniformity of the electrode. This is followed by a slitting operation for proper electrode sizing.
Given the intricate nature of the manufacturing steps outlined above, the binder material’s characteristics are highly significant and must conform to strict criterion. Primary characteristics of relevance are: (i) ionic conductivity, (ii) tensile strength, (iii) water absorption, (iv) adhesion property, (v) swelling in electrolyte, (vi) melting point, (vii) molecular weight distribution, (viii) dissolution properties, (ix) crystalline properties and (x) purity.