High-Performance Magnesium/Lithium Hybrid-Ion Battery Using NiS₂ Nanosheet-Coated Cu₂S Cubes as a Cathode Material

Magnesium/lithium hybrid-ion batteries (MLHBs) are considered promising owing to their high theoretical capacity and good safety and a broad range of magnesium resources; however, nonideal cathode materials and electrolytes restrict their development. Here, a composite composed of NiS₂ nanosheet-coated Cu₂S (Cu₂S@NiS₂) cubes is developed as a cathode material, which improves conductivity and accommodates volume change, achieving high and stable electrochemical performances. Also, we develop a LiCl-introduced all-phenyl-complex electrolyte (APC-LiCl), exhibiting a wide electrochemical window, stable cycling properties, and enhanced Mg dissociation/deposition compared to LiBF₄ or LiTFSI-induced APC systems. The constructed MLHB exhibits a high energy density of 330 Wh kg^-1 on an active cathode material basis when cycling at 0.3 A g^-1, a stable specific capacity of 215 mAh g^-1 after 400 cycles at 0.5 A g^-1, and excellent temperature tolerance and rate performance, enabling our findings to be broadly applied for developing emerging energy-storage systems.