(281b) Obtaining Structural Information of Carbon Black in Complex Mediums for Energy Storage Systems with Rheo-Electric Measurements

Carbon black (CB) serves as an important carbon nanomaterial given its industrial applications such as fuel cell catalyst inks, flow battery conductive additives, and lithium-ion battery slurries. It is known that when formulated into suspensions, CB shows complicated rheological and electrical behaviors originating from evolving microstructure of CB particles and both the rheological and electric properties are important to engineer and optimize the performance of energy storage systems. While much is known about CB both at rest and under flow in simple mediums, the rheology and the electric properties of CB in complex mediums need to be investigated as CB suspensions are usually added with other components when formulated into industrial products.

Specifically, slurries of carbon black used in lithium-ion battery manufacturing incorporate dissolved polymers and active materials. We used rheo-electric measurements first to show that the addition of polymers modifies the structure of CB agglomerates through the indirect effect on the solvent viscosity. Simultaneous electric measurements were conducted on these CB/polymer suspensions in shear flow as a function of carbon and polymer composition. We found that the CB agglomerate size information can be derived from normalized suspension viscosity through rheological measurements. Additionally, the further validation of such size information is evident in the dielectric strength of the relaxation process obtained from the electric measurements. We further conducted rheo-electric measurements on lithium-ion battery slurries which contain CB, polymers, and active materials. From the dielectric spectrums, we obtained the structure and the dispersion of CB within the battery slurries, which were shown to be strongly correlated with the measured rheology.

These findings are valuable to energy storage systems containing CB as the dispersion of CB can be predicted and controlled with tunable processing conditions to optimize the performance. In addition, the unique insight gained from the rheo-electric measurements can be further extended to engineer the next-generation of CB nanomaterials for energy storage systems.