Flow batteries are a relatively less common battery system that provides the opportunity to decouple the power output and energy storage components within the cell. Such systems are well-suited to stationary energy applications, where the capability to independently scale power and energy provides operational advantages. These systems have primarily been restricted to stationary applications where the footprint of the battery is not restricted, due to the relatively low energy density for the commercial flow batteries. Established flow battery systems have been demonstrated at very large scales; however, one of their limitations for moving into applications that require higher energy density is that the energy stored per volume of electrolyte is limited by the solubility of the dissolved redox species within the electrolyte. Above the solubility limit, inactive precipitates form that do not contribute to electrochemical capacity but provide operational complications such as increased electrolyte viscosity.
Recently, our research group and others have explored flow battery systems where the electrolyte intentionally starts with solid material dispersed in the liquid phase, and the solid particles in the dispersion are the electroactive material contributing to the electrochemical capacity. Starting with solid electroactive materials in principle increases the energy density of the flow batteries substantially, but new challenges arise with regards to the rheological properties of the electrolyte and the power density in these systems. This talk will discuss the different strategies that have been proposed to take advantage of loading solid particles in electroactive flow battery systems. In addition, the use of similar flowing dispersions to characterize electroactive materials will be described.