Multivalent cationic and anionic mixed redox of an Sb2S3 cathode toward high-capacity aluminum ion batteries

Abstract

The conventional cationic redox centers of transition-metal-based cathodes are reaching their theoretical capacity limit, which cannot match the ultra-high specific capacity contributed by the three-electron transfer reaction of an Al anode (2980 mA h g⁻¹, 8056 mA h cm⁻³), severely restraining the development of high-energy rechargeable Al-ion batteries (RAIBs). In this work, we propose the multivalent cationic and anionic mixed redox chemistry of Sb₂S₃ as a promising way out of this problem. The energy storage is induced by the cumulative Sb-related cationic (Sb(+3) ⇔ Sb(+5)) and S-related anionic (S(−2) ⇔ S(0)) mixed 10-electron transfer reversible redox reaction during the charge/discharge process, which has been elucidated here by extensive electrochemical measurements and characterizations. Furthermore, excellent electrochemical performances are realized due to the carbon-based interlayer effectively blocking the charging products of the Sb-based cationic cluster (SbCl₄⁺), by a dual defense mechanism that integrates the physical barrier of the porous structure and the powerful chemical adsorption ability of the oxygen groups. The Sb₂S₃ cathode could deliver a discharge specific capacity of 756 mA h g⁻¹ at 100 mA g⁻¹. The finding is that the joint multivalent cationic and anionic redox chemistry proposed in this work opens up new opportunities for designing high-performance electrodes for advanced rechargeable batteries.