Interfacial engineering of Bi₂Te₃/Sb₂Te₃ heterojunction enables high–energy cathode for aluminum batteries

Rechargeable aluminum batteries (RABs) have been regarded as a low-cost and safe candidate for electrochemical energy storage. However, the high charge density of Al³⁺ causes its sluggish diffusion and the large size of AlCl₄⁻ renders the capacity of the cathode low. Here we propose heterostructured Bi₂Te₃/Sb₂Te₃ nanoflakes by interfacial engineering, constructing a heterojunction that induces a built-in electric field among the interface between two phases to realize rapid charge transfer, fast ion diffusion, and high capacity of cathode. Note that the operational mechanisms of heterostructured Bi₂Te₃/Sb₂Te₃ cathode are based on the reversible intercalation/deintercalation of Al³⁺ ions with the redox process between Bi³⁺ and Bi⁵⁺ upon discharge and charge. As expected, the heterostructured Bi₂Te₃/Sb₂Te₃ nanoflakes deliver superb Al-storage property and rate capability, which is among the best comprehensive performances of cathodes in RABs.