1999 Volume 67 Issue 6 Pages 695-699
To decrease the reaction polarization of the cathodic reaction of Cl2 + 2e− → 2Cl− in Al-Cl2 electrochemical cell in NaCl-KCl melt at 1023 K, we developed a cell system with a vertically rotating electrode composed of sliced graphite disks which are partially immersed in the melt. The apparent reaction resistance of the cathodic reaction was evaluated from transient potential and current changes of the cell. The reaction resistance decreases with an increase of the number of the graphite disks. The resistance is a function of the rotation rate of the electrode and exhibits the minimum value around a rotation rate of 20 rpm. The dependence on the rotation rate may be explained from Cl2 concentration in a thin melt layer formed on the graphite electrode during exposure to Cl2 gas phase. The rotation may introduce a continuous supply of the thin melt layer with a high concentration of Cl2 to a reaction place at a meniscus part on the graphite electrode. However, if the rotation rate is too high, the exposure time of the thin melt layer to Cl2 gas is not enough to establish an equilibrium concentration of Cl2 in the layer.
