(230ae) A New Dielectric Rheosans Instrument for the Simultaneous Interrogation of Rheology, Microstructure, and Electronic Properties of Flow Battery Electrodes

Authors: 
Richards, J. J. - Presenter, National Institute of Standards and Technology
Butler, P., National Institute of Standards and Technology
Inexpensive grid-scale storage remains a major hurdle slowing the wide-scale adoption of renewable energy technologies. Flow Batteries have been proposed as one viable solution to this problem. Whereas, the capacity of a traditional battery is limited by its packaging, flow batteries pump redox active fluids from external storage tanks through a flow cell where electricity is extracted or stored via reversible redox reactions. One promising flow battery technology is the semi-solid flow battery (SSFB). Instead of using a soluble electrolyte, SSFBs incorporate dispersions of electrochemically active particles as the active material allowing for higher specific power densities. In addition to the electrochemically active species, carbon black is typically incorporated into the flow battery electrode as a conductive additive to provide the necessary electrical percolation throughout the electrode. While carbon black can allow for electrical percolation at relatively low volume fractions, the rheological properties of these dense slurries have a detrimental effect on the flow battery performance. In order to understand the intrinsic link between microstructure, rheology and conductivity in carbon black suspensions, we have developed a new dielectric RheoSANS instrument. We have fabricated a Couette geometry capable of performing RheoSANS measurements while the electrical properties of these carbon black slurries are monitored. By measuring the microstructure and electrical properties of carbon black network as function of the shear rate we have begun to understand the intimate link between the flow properties and electrical percolation in these materials. Our findings will open up new pathways for the optimization of these promising energy storage technologies.