Novel Insight into Rechargeable Aluminum Batteries with Promising Selenium Sulfide@Carbon Nanofibers Cathode

Abstract Due to the unique electronic structure of aluminum ions (Al³⁺) with strong Coulombic interaction and complex bonding situation (simultaneously covalent/ionic bonds), traditional electrodes, mismatching with the bonding orbital of Al³⁺, usually exhibit slow kinetic process with inferior rechargeable aluminum batteries (RABs) performance. Herein, to break the confinement of the interaction mismatch between Al³⁺ and the electrode, a previously unexplored Se_2.9S_5.1‐based cathode with sufficient valence electronic energy overlap with Al³⁺ and easily accessible structure is potentially developed. Through this new strategy, Se_2.9S_5.1 encapsulated in multichannel carbon nanofibers with free‐standing structure exhibits a high capacity of 606 mAh g⁻¹ at 50 mA g⁻¹, high rate‐capacity (211 mAh g⁻¹ at 2.0 A g⁻¹), robust stability (187 mAh g⁻¹ at 0.5 A g⁻¹ after 3,000 cycles), and enhanced flexibility. Simultaneously, in/ex‐situ characterizations also reveal the unexplored mechanism of Se_xS_y in RABs.