Evaluation of Electrochemical Properties of Aluminum Electrolytes with Ammonium Salt Using an Ultramicro Disk Electrode

Cyclic voltammetry of a DMSO 2 –AlCl 3 electrolyte was performed using an ultramicro disk electrode to evaluate the effects of ammonium salts on the Al electrodeposition reaction. A side reaction in the electrolyte at potentials more negative than −0.8 V (vs Al-wire) was found to suppress the Al electrodeposition reaction. The addition of even a small amount of NH 4 Cl promoted an Al electrodeposition reaction, which proceeded at more positive potentials than the side reaction. With the excessive addition of tetramethylammonium chloride (TMAC) electrolyte, the Al electrodeposition reaction was also suppressed, proceeding in the negative potential region where a side reaction occurs. In the electrolyte containing 0.02-mol NH 4 Cl and 1.0-mol TMAC, a decrease in the deposition overpotential on the reducing side and an increase in the dissolution current on the oxidizing side were observed simultaneously.