Mass‐Transfer Study of Carbon Felt, Flow‐Through Electrode

The mass‐transfer characteristics of a carbon felt, flow‐through electrode that has potential application for the positive electrode in zinc‐bromine batteries were studied. The electrochemical technique of limiting current measurements for the cathodic reduction of bromine in excess supporting electrolytes was used. In an electrochemical cell with perpendicular flow of electrolyte and current, limiting currents that were proportional to the electrolyte velocity, , where , which was dependent on the electrode thickness but independent of the concentration of reactant species, were obtained at low Reynolds numbers. Analysis of the data using a model that relates the conversion efficiency of a porous electrode to a dimensionless group, , which contains experimental parameters such as porosity, pore diameter, flow rate, and diffusion coefficient, showed good agreement.