Suppressing corrosion in primary aluminum–air batteries via oil displacement

Abstract

Primary aluminum–air batteries boast high theoretical energy densities, but negative electrode corrosion irreversibly limits their shelf life. Most corrosion mitigation methods are insufficient or compromise power and energy density. We suppressed open-circuit corrosion by displacing electrolyte from the electrode surface with a nonconducting oil during battery standby. High power and energy density are enabled by displacing the oil with electrolyte for battery discharge. The underwater-oleophobic wetting properties of the designed cell surfaces allow for reversible oil displacement. We demonstrate this method in an aluminum–air cell that achieves a 420% increase in usable energy density and 99.99% reduction in corrosion, which lowers self-discharge to a rate of 0.02% a month and enables system energy densities of 700 watt-hours per liter and 900 watt-hours per kilogram.