Designing fluorinated interphase for rechargeable aqueous Al batteries

Abstract

Aqueous aluminum batteries (AABs) have been attracted increasing attentions as a promising alternative for next-generation large-scale energy storage systems owing to their low-cost, intrinsic safety and high theoretical specific capacity. However, the practical application of AABs is still hindered by the side reactions at anode side including hydrogen evolution reaction (HER) and metallic Al corrosion/passivation. Here we found that the Al anode with fluorinated interface (FAl) through water and trifluoroacetic acid treatment can accelerate Al anode kinetic with low overpotential. Meanwhile, the stable and hydrophobic interphase can protect Al anodes from directly contact with corrosive aqueous electrolytes, achieving a deminished HER and long-term cycling stability. The symmetrical batteries with FAl can cycle reversibly for over 1000h, nearly 10 times higher than untreated Al. Furthermore, the aqueous Al batteries with PTO (pyrene-4,5,9,10-tetraone) as cathode achieved a high initial capacity of 350 mAh g-1 and 237.8 mAh g-1 after 60 cycles. This work provides new insight into design principles for high safety and long-term stability AABs.