Understanding the reversible electrodeposition of aluminum in low-cost room-temperature molten salts

Aluminum is the most earth-abundant metal, trivalent, inert in ambient humid air, and has a density approximately four-times that of lithium at room temperature. These attributes make it an attractive material for cost-effective, long-duration storage electrical energy batteries. Scientific discoveries past decade have established secondary Al batteries can be created by paring anode with graphite or transition metal oxide cathode, imidazolium-based, room-temperature ionic-liquid-Aluminum chloride electrolytes. Here we report findings from systematic study sheds light on structural requirements, physicochemical, transport properties ionic liquid electrolytes responsible high reversibility battery anodes. We find important interfacial these achieved other electrolytes, including ammonium-based molten salts are available costs as much twenty-times lower than liquid-Aluminum melt. High ammonium- imidazolium-based specifically shown to require critical ratio solvation species, where Lewis acidity beneficial reactions continuously etch alumina resistive layer form solid electrolyte interphase anode. further successful development new families support also provides good platform detailed studies working mechanisms intercalation cathode using X-ray absorption spectroscopy. Our therefore open opportunities developing simple, enable storage.