Reversible passivation in primary aluminum-air batteries via composite anodes

Despite the fact that primary aluminum-air have extraordinary theoretical energy densities, their shelf life is irreversibly restricted by anodic hydrogen evolution corrosion. However, current corrosion-suppression solutions usually make significant sacrifices in terms of energy and power density. We prepared carbonaceous nanomaterial-reinforced aluminum matrix composites as anodes for reversible passivation, preventing self-corrosion in an open-circuit state. Homogeneous microstructures of the composites induced by severe plastic deformation allow for the formation of passivation films against hydrogen evolution reactions. The strong bonds between magnesium-containing aluminum hydroxides and fluorinated graphene nanoplatelet enhance the stability of the nanosphere-structured passivation layer. The fluorinated nano-reinforcements enable reversible adsorption and exfoliation induced by the discharge process to realize reversible passivation mechanisms. This composite anode in aluminum-air cells achieves a 424% increase in effective energy density during intermittent discharge, which possesses a considerable anode energy utilization of 37.5% and an intermittent discharge efficiency of 95.3 ± 3.1%.