Porous Cu9S5 nanonets as an efficient cathode material for high-capacity rechargeable magnesium batteries

Abstract

Rechargeable magnesium batteries (RMBs) have garnered special interest as a promising energy-storage technology owing to elemental abundance and high theoretical volumetric capacity of Mg. Their development, however, is still limited owing to the absence of capable cathode materials for any potential applications. Herein, the Cu₉S₅ nanonets are synthesized by a facile hydrothermal treatment, and then used as a feasible cathode for RMB, which can deliver a high initial discharge specific capacity of 420.1 mAh g^–1 at 100 mA g^–1, and an impressive reversible capacity of 279.2 mAh g^–1 after 48 cycles at 50 mA g^–1. This outstanding performance is attributed to the unique net-like nanostructure of Cu₉S₅, which facilitates the diffusion and reaction kinetics of Mg²⁺ ions. Moreover, the Mg-storage mechanism containing a two-step conversion reaction was also discussed. The present study will encourage further investigation on the optimization of cathode materials for high-capacity Mg batteries.