Pitaya-like carbon-coated ZnS/carbon nanospheres with inner three-dimensional nanostructure as high-performance anode for lithium-ion battery.

The electrochemical performance of ZnS-based anode materials for Li-ion storage is far from satisfactory due to the incomplete protection of carbon against the volume change. To address this issue, we synthesized a pitaya-like carbon-coated ZnS/carbon nanosphere with rich mesopores (denoted as ZnS/C@C) that can be a promising anode material for Li-ion storage. ZnS/C@C were synthetized via a facile hydrothermal method followed by a chemical vapor deposition process. In this novel hierarchical architecture, the internal carbon framework with mesoporous structure acted as a cushion matrix, effectively preventing ZnS from fracturing and agglomerating during the repeatedly cycling. The outer carbon-coating layer with a thickness of ∼10 nm as a buffer cage accommodated the large strain caused by the volume change. Meanwhile, both the inner carbon framework and the outer carbon-coating layer provided ZnS/C@C with abundant electrical pathways that boosted the reaction kinetics efficiently. The porous structure allowed the infiltration of electrolyte and decreased the transport length of Li ions. Merited by the optimized structure, the ZnS/C@C anodes showed exceptional rate capability (751 mAh g-1 at 1000 mA g-1) and cycling stability (659 mAh g-1 at 1000 mA g-1 over 1200 cycles). An ultrahigh reversible capacity of 949.6 mAh g-1 at 100 mA g-1 was achieved.