Aluminum Electrodeposition from Chloride-Rich and Chloride-Free Organic Electrolytes

The corrosivity of chloride-based electrolytes is a major shortcoming in the practical realization of rechargeable aluminum batteries. Herein, the effect of Cl– on Al speciation and electrochemistry in tetrahydrofuran (THF) was measured by employing theoretical and experimental approaches for three systems: Al(OTF)3/THF, Al(OTF)3 plus LiCl in THF, and AlCl3/THF. The high consistency between measured and computed spectroscopic aspects associated with Al(OTF)3/THF electrolyte provided both a rationale for understanding Al complex-ion formation in a Cl–-free environment and an approach for examining the effect of Cl– on Al speciation. Room-temperature Al plating was achieved from dilute solutions ([Al] = 0.1 M) at potentials ≥ 0 V (vs Al/Al3+). Cl– is found to enable facile Al plating and SEM reveals that Al is electrochemically deposited as nanocrystalline grains.