Highly Conductive Colloidal Carbon Based Suspension for Flow-Assisted Electrochemical Systems

Abstract

Colloidal carbon based suspension electrodes are gaining increased attention for large-scale energy storage applications, and particularly for flow-assisted electrochemical energy storage systems. In the latter, they serve as flowable electrodes in an electrolyte solution of flow batteries, or flow capacitors. They can also be used for applications other than energy storage such as capacitive deionization of water. However, developments of such suspensions remain challenging. The suspensions should combine low viscosity and high electronic conductivity for optimized performances. In this work, we report a flowable aqueous carbon dispersion which exhibits a viscosity of only 2 Pa.s at a shear rate of 5 sec-1 for a concentration of particles of 7 wt%. At this concentration, the suspension forms a conductive network and displays an electronic conductivity of 65 mS/cm, nearly two orders of magnitude greater than previously related materials. The investigated suspensions are stabilized by sodium alginate and arabic gum in the presence of ammonium sulfate. Experiments under flow demonstrate that the suspensions remain highly conductive upon shearing. Their use in flowable systems for the storage and discharge of electrical charges is demonstrated.