Room-Temperature Electrodeposition of Aluminum via Manipulating Coordination Structure in AlCl3 Solutions

J Phys Chem Lett. 2020 Feb 20;11(4):1589-1593. doi: 10.1021/acs.jpclett.0c00256. Epub 2020 Feb 12.

Abstract

The coordination mechanism of chloroaluminate species in aluminum chloride (AlCl3) solutions in γ-butyrolactone (GBL) is investigated using electrochemical, spectroscopic, and computational methods. The liquid-state 27Al NMR spectroscopy shows a sequence of new species generated in the AlCl3-GBL solutions with increasing AlCl3/GBL ratio. Ab initio molecular dynamics simulation reveals the dynamic coordination process between GBL and AlCl3, and the resultant chloroaluminate species are identified as [AlCl2·(GBL)2]+, AlCl4-, AlCl3·GBL, and Al3Cl10-. The species are further confirmed by surface enhanced Raman spectroscopy combined with calculated Raman spectra from methods based on density functional theory. Electrochemical deposition of Al is achieved from the AlCl3-GBL solution containing Al3Cl10-, which is one of the few noneutectic electrolytes for room-temperature Al deposition reported to date.