Rational surface engineering of MXene@N-doped hollow carbon dual-confined cobalt sulfides/selenides for advanced aluminum batteries

Abstract

Rechargeable aluminum batteries (RABs) based on multivalent ion transfer have attracted great attention due to their large specific capacities, natural abundance, and high safety of metallic Al anodes. However, the poor cycling performance and sluggish diffusion kinetics severely restrict the development of RABs. In this paper, the mechanism of impacting the rechargeable ability of Co₉S₈ electrodes is demonstrated to be linked to the production of soluble active cobalt species upon both chemical dissolution and electrochemical conversion processes. To avoid the excessive loss of active species and structural pulverization, rational surface engineering of MXenes and N-doped hollow carbon dual-confined Co₉S₈ nanoparticle composites (Co₉S₈ NP@NPC@MXene) is designed to enhance the aluminum storage properties. The cell delivered a high reversible capacity (277 mA h g⁻¹ at 0.1 A g⁻¹ after 100 cycles), excellent rate-cycle capability up to 1 A g⁻¹, and low polarization. Furthermore, this strategy is also successfully demonstrated in a CoSe₂ electrode that presents a high discharge capacity of up to 288 mA h g⁻¹ at 1 A g⁻¹ as well as a desirable capacity retention of approximately 220 mA h g⁻¹ after 300 cycles, demonstrating its feasibility and versatility. This elaborate work would be of great significance for the further development of advanced chalcogenides for RAB cathodes.