NiCo2S4 multi-shelled hollow polyhedrons as high-performance anode materials for lithium-ion batteries

NiCo2S4 single-shelled hollow polyhedrons (SSHPs) and double-shelled hollow polyhedrons (DSHPs) were synthesized by the same metal-organic-framework-engaged strategy that took advantage of the unique reactions of zeolitic imidazolate framework-67 and Ni(NO3)(2), H2O, thiacetamide. It was found by XRD, SEM, TEM that the synthesized NiCo2S4 materials showed the hollow polyhedron structure assembled with nanocrystalline (the size was around 10-15 nm), and numerous mesopores existed among these nanocrystalline. As anode materials for lithium-ion batteries, NiCo2S4 SSHPs and DSHPs exhibited excellent cycling stability, but DSHPs were remarkably superior to SSHPs in terms of capacity performance and rate capability. At 0.1C, DSHPs could deliver the discharge capacity of 770.3 mAh g(-1) at the 100th cycle, and the average discharge capacity over 100 cycles reached 745.5 mAh g(-1). When the current came back to 0.1C after rate measurements, NiCo2S4 DSHPs could stably deliver the discharging capacity of 712.0 mAh g(-1), reaching 92.1% of that at the initial 0.1C. The superior Li-storage performance should be attributed to the nanocrystalline, mesopore, and multi-shelled hollow polyhedron structure. The unique NiCo2S4 multi-shelled hollow polyhedrons exhibit great potential as anode materials for high-performance lithium-ion batteries. (C) 2019 Elsevier Ltd. All rights reserved.