Experimental Study of Electronic and Ionic Conductivity of a Carbon-Based Slurry Electrode Used in Advanced Electrochemical Energy Systems

Focusing on the application of carbon slurry electrodes in advanced electrochemical power and energy storage systems, the electrical conductivity of such electrodes is thoroughly investigated experimentally. A slurry electrode made from steam-activated Norit is analyzed to estimate its electronic and ionic conductivities separately. A single-pass rectangular flow channel with three different widths of 4.1, 3.6, and 3.1 cm is used to investigate the effect of the flow channel geometry on slurry electrode conductivity. Three different slurry concentrations of 5, 10, and 15 wt % are investigated, while electronic and ionic conductivities are separately measured using distilled water and sulfuric acid as electrolytes. The charge conduction improvement due to the availability of more charge-carrying particles in the slurry is quantified, and it is shown that up to about 220 and 120% increase in electronic conductivities can be achieved by increasing carbon loading from 5 to 10 and 15 wt %, respectively. Analysis of slurry conductivity variations from a static condition to a flow rate of 280 mL min–1 with different channel widths and concentrations shows that the slurry conductivity reaches a maximum value at an intermediate flow rate and is then gradually decreased. The optimum working condition of a slurry electrode is finally discussed.