Effect of Various Components on Time-Dependent Rheological Behavior of Cathode Slurries for Lithium-Ion Batteries

The multi-interactions between nanoparticles and micro-particles, as well as polymers are responsible for complex rheological behavior in electrode slurry, which has crucially influenced the quality and lifetime of lithium-ion batteries. To clarify the shear- and time-dependent rheological behavior of the multi-component slurry, the effect of various components on the yield stress, viscosity, and thixotropic time scales has been investigated by steady-state and transient step experiments. The results demonstrate that the amounts of added carbon black, polymeric binders, and active material play a significant role in the rheological properties. In the steady-state tests, the viscosity of the slurry increases with the increase of the carbon black, polymer, and active material content. However, the yield stress of the slurry only distinctly increases when the carbon black and polymer are increased, while it is virtually unaffected by large particles of the active material. In the transient tests, the destroyed timescale rises and the recovery timescale reduces as the carbon black, polymer, and active material content are increased. The quantitative relationship between various components and rheological behaviors will be useful for the preparation and coating process of slurry.