A hollow Core-Shell Cu2S@C nanoboxes for High-Performance electrochemical sodium storage

Aiming at the poor intrinsic conductivity and huge volume expansion of transition metal sulfides, carbon-coated cuprous sulfide hollow nanoboxes (Cu2S@C) with core-shell structure were designed via co-precipitation, facial carbon coating and in-situ sulfurization methods, and exhibited significantly improved electrochemical properties applied as sodium ion battery anode. The uniformly coated carbon shell can enhance the electrolyte infiltration, promote charge transfer efficiency, accelerate electrochemical conversion redox kinetics. The conversion reaction reversibility of restricted Cu2S cores show a significant improvement benefitting from accelebrating ion diffusion and spatial limitation. During the sulfidation, robust chemically and electronically bonded connections such as C-S moieties formed between the two phases, creating interconnected channels that facilliate rapid charge transfer kinetics and optimize structural durability. Moreover, the hollow core-shell structure can provide a buffer space for tolerating volume expansion and preventing agglomeration arising from the repeating Na+ insertion/desertion process, which can availably enhance cyclic stability. Thanks to the synergistic effect between strong interfacial coupling and hollow core-shell structure, the Cu2S@C composite can deliver an improved Na+ storage performance. At the high current density of 1.0 A/g, the Cu2S@C anode could exhibit a specific capacity of 100.08 mAh/g, which is significant ameliorative than Cu2S counterpart (only 11.6 mAh/g).