Promising aluminium batteries keep failing because the liquid inside creates a death grip on the metal ions.
April 24, 2026
Original Paper
Strongly Coordinated Al3+ Complex Formation Prevents Reversible Electrochemical Cycling in Haloaluminate-Free Ionic Liquids
ChemRxiv · chemrxiv.15002314/v1
The Takeaway
Aluminium is a cheap and safe alternative to lithium for high capacity batteries, but finding the right electrolyte has been a major hurdle. New research shows that in certain non-corrosive liquids, aluminium ions bond so tightly to other chemicals that they can't be used to store power. This death grip causes the battery to produce hydrogen gas instead of plating the metal during charging. This discovery explains why years of attempts to fix these batteries with simple additives have failed. It forces the industry to stop trying to tweak these specific liquids and look for entirely new chemical families.
From the abstract
Advancements in aluminium-ion batteries require new non-corrosive electrolytes with high oxidation stability. Recently, haloaluminate-free electrolytes based on Al(OTF)3 and Al(TFSI)3 salts have attracted interest for aluminum electrochemistry; nevertheless, reversible Al0/3+ cycling in these systems remains debated. This work reveals that Al0 electrodeposition universally fails in Al(OTF)3 and Al(TFSI)3 based ionic liquid electrolytes because Al3+ spontaneously extracts F- from anion and OH- fr