(126F) Quantifying the Rheological Effect on the Capacitance of Carbon Suspensions

Wind and solar renewable energy sources are becoming competitive options compared to fossil fuels but new innovation of grid-scale energy storage systems are needed to properly implement them. Semi-solid flow batteries (SSFBs), batteries composed of a slurry active material, are a possible solution due to the decoupling of the battery energy capacity and power density. Conductive carbon black has high potential as a slurry material due to its low capital and high surface area for optimizing capacitance. While the rheological and electrical responses of conductive carbon black slurries have been characterized, there has been seldom reports on the two measurements in tandem. To this end, this research focuses on creating a custom-built electrochemical cell capable of performing electrical measurements while a slurry sample is being sheared. The electrochemical cell, built using 3D printing, attaches onto a rheometer, allowing electrical measurements from a VersaSTAT potentiostat to travel through the rheometer. Reproducible rheological data was generated using a solvent trap to minimize evaporation and a pre-experiment procedure used to erase the sample shear history. The capacitance of a carbon black slurry in 35 mg/ml NaCl solution under shear between 0 to 1250 1/s shear rate was calculated utilizing equivalent circuit modeling of Nyquist plots obtained from electrical impedance spectroscopy (EIS). The results showed an increase in capacitance as shear rate increased, which is inline with previous studies. We showcased that high shear rates are necessary for reasonable capacitance to be achieved within SSFB, influencing future design parameters for SSFBs.