Hierarchical Copper Sulfide Porous Nanocages for Rechargeable Multivalent-Ion Batteries.

Copper sulfide (CuS) has been identified as a promising positive electrode material for some multivalent-ion batteries (such as the magnesium-ion battery) because of its high theoretical capacity, environmental friendliness, and wide availability. However, the clumsy multivalent-ion with high polarity inclines toward sluggish ion insertion/de-insertion, leading to inadequate electrochemical performance. In this work, the hierarchical CuS porous nanocages are successfully fabricated via a facile one-step room-temperature liquid-phase process and evaluated as positive electrode materials for rechargeable magnesium batteries. Owing to the structural advantages, a high reversible magnesium storage capacity of 228 mA h g-1 is attained, which is superior to the previously reported results under similar conditions. Besides, the application of CuS as positive electrode materials for calcium-ion, zinc-ion, iron-ion, and aluminum-ion batteries is investigated. The hierarchical CuS porous nanocages display promising electrochemical performance in those multivalent-ion battery systems. Our work proves the superiority of the nanostructure design in improving the electrochemical performance of positive electrode materials for multivalent-ion batteries.