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

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) double left right arrow Sb(+5)) and S-related anionic (S(-2) double left right arrow 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.