Hierarchically porous Zn-Co-O NCs-in-carbon hollow microspheres with high rate-capacity and cycle stability as anode materials for lithium-ion batteries

Publication date: 5 March 2018
Source:Journal of Alloys and Compounds, Volume 736
Author(s): Chuan Ding, Xiaoshu Jiang, Xiaohong Huang, Hu Zhang, Wenqing Zhong, Yifei Xia, Chongjiang Dai
Zn-Co-O/C hollow microspheres composed of center hole with an average size of 400 nm and ∼30 nm thicked porous carbon walls inlaid homogenously with ∼5.2 nm Zn-Co-O nanocrystals are successfully prepared for the first time via a Na-citrate mediated solvothermal method and a subsequent annealing process of Zn-Co-ethylene glycolate (Zn-Co-EG) precursor. The obtained powders were systematically characterized by XRD, IR, FESEM, TEM, BET and Raman techniques. The data indicate that the polymerization reaction of Zn-Co-EG crystals confined by Na-citrate should be responsible for the formation of the hollow microspherical precursors, which are then converted into the hierarchically porous Zn-Co-O/C hollow microspheres with complex microstructures after annealing at 450 °C for 3 h. These porous Zn-Co-O/C hollow microspheres used as an anode material for lithium-ion batteries exhibit a high reversible capacity of 991.7 mAh g⁻¹, 81.6% of the second cycle discharge capacity after 200 cycles at 1 A g⁻¹, and a high-rate delivery of 823.4 mAh g⁻¹ after 1000 cycles at 4 A g⁻¹. The superior performance of Zn-Co-O/C hollow microspheres is mainly attributed to the local dynamic confinement of tiny Zn-Co-O nanoparticles in the ultrathin porous carbon matrix.

Graphical abstract

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