High efficient electrolytic production of Al-Li alloy by using Li sub 2 CO sub 3 as a source of lithium

• Published in: Keikinzoku Vol. 48; no. 3; pp. 138 - 142
• Main Authors: Sato, Y, Kariya, H, Suzuki, T, Saito, S, Yamamura, T
• Format: Journal Article
• Language: Japanese
• Published: 01.03.1998
• ISSN: 0451-5994

The behavior of Li sub 2 CO sub 3 in molten LiCl electrolyte has been studied to produce Al-Li alloys electrolytically by using Li sub 2 CO sub 3 as a source of Li. The Li sub 2 CO sub 3 is a promising raw material of lithium because of its low cost, non-hygroscopic property, high purity, etc. compared with LiCl. An anode compartment, which should prevent the cathode from the infiltration of the anolyte with keeping the electrical contact, was formed by using porous Al sub 2 O sub 3 crucible. By the electrolysis, lithium deposited at molten aluminum cathode to make an Al-Li alloy and the cathodic potential shifted to more positive potential than that of deposition of pure Li because of lower activity of Li in the alloy. On the other hand, the carbonate ion reacted with graphite anode and the anodic potential decreased by almost 1.2-1.3 V than that of Cl sub 2 evolution when feeding small pieces of Li sub 2 CO sub 3 into the anode compartment. Therefore, the potential required to obtain the Al-Li alloy is almost half of the theoretical decomposition potential of LiCl. Current efficiency of cathode was more than 90% which was comparable to the electrolysis using only LiCl electrolyte. Main component of the exhaust from the anode was CO sub 2 with small amount less than 3% of CO. Carbon consumption was almost the theoretical minimum which was 0.5 mol to one mol Li sub 2 CO sub 3 . These results suggest that the use of Li sub 2 CO sub 3 as a raw material of lithium is very effective to produce high-quality Al-Li alloy with low cost.