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_2.9 S_5.1 -based cathode with sufficient valence electronic energy overlap with Al³⁺ and easily accessible structure is potentially developed. Through this new strategy, Se_2.9 S_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_x S_y in RABs.