Meaning
Constant angular deformation applied to a fluid or semi-solid material to measure its flow resistance under steady flow conditions. Applying continuous shear strain to electrode slurries reveals their viscosity profiles, ensuring they can be pumped and coated onto current collectors without clogging. The measurement defines the upper limit of stable flow before the material begins to aggregate or separate.
Rheological Behavior
Fluid dynamics dictate how the active materials and binders distribute themselves in the solvent. A stable mixture depends on thinning behavior under flow.
Processing Impact
Manufacturing speeds depend directly on maintaining a steady shear rate during the application of the wet active material to the metal foil. If the continuous shear strain rate is too low, the coating may exhibit thickness variations that degrade the electrochemical performance of the finished electrode. High-speed coating lines run close to the limit of shear stability, where any turbulence can cause uneven loading.
Structural Integrity
Consolidation of the slurry after deposition requires rapid recovery of the original viscosity to prevent running or dripping. This process, known as thixotropic recovery, determines how well the wet line maintains its shape before entering the drying oven. If the slurry does not rebuild its structure quickly, the active material will pool at the edges of the foil, creating uneven energy density.
