Aluminum-air battery prototype

A prototype of a long-lived battery relies on oil to protect its aluminium electrodes. Credit: Brandon J. Hopkins

Energy

Oil foils corrosion in high-capacity batteries

Swapping out the electrolyte promises to extend the lifespan of aluminium–air batteries.

Non-rechargeable batteries that rely on a reaction between aluminium and atmospheric oxygen can hold much more energy than their conventional lithium–ion counterparts. A new tweak to the design of such batteries might overcome their greatest limitation: a short shelf life.

When an aluminium–air battery is not in use, its electrodes corrode, allowing unwanted electric discharge that shortens the battery’s lifespan. Brandon Hopkins at the Massachusetts Institute of Technology in Cambridge and his colleagues developed an aluminium–air battery that employs a conventional electrolyte while the battery is in use but, during storage, replaces the electrolyte with oil.

The battery achieves an energy-storage capacity of almost 900 watt-hours per kilogram — a capacity that is comparable with that of other aluminium–air battery designs — while reducing corrosion by 10,000-fold compared with other aluminium–air batteries. The authors suggest that such a battery could be used in long-range drones and for off-grid electricity generation.