Hierarchical NiCoO2@Ni3S2 core/shell nanoflakes arrays with superior capacitive performances for energy storage

By Deng, Xiaoli; Zhou, Qingxiao; Huang, Haifu; Zhou, Wenzheng; Liang, Xianqing; Li, Guangxu; Guo, Jin; Tang, Shaolong
Published in Applied Surface Science 2019

Abstract

Herein, it reports the design and synthesis of NiCoO2@Ni3S2 core/shell arrays on Ni foam using a two-step method of hydrothermal method and electrodeposition. The hetero-structures are composed of NiCoO2 flakes as the core-material and Ni3S2 ultrathin nanosheets as the shell-material. Due to the unique core/shell hetero-structure and positive synergistic effect of two components, hierarchical NiCoO2@Ni3S2 arrays exhibit excellent capacitive performance as energy storage materials. The mass specific capacity of NiCoO2@Ni3S2 is as high as 1599.5C g?1 at 1.0 A g?1, which is higher than the sum of the capacity of the two samples NiCoO2/NF(640.0C g?1) and Ni3S2/NF(695.3C g?1). NiCoO2@Ni3S2/NF also shows a very high areal specific capacity of 4.06 C cm?2. Therefore, NiCoO2@Ni3S2 arrays greatly releases the energy storage potential of the NiCoO2 and Ni3S2 materials in supercapacitors. Furthermore, a hybrid supercapacitor device fabricated using NiCoO2@Ni3S2/NF as positive electrode and the graphene as negative electrode possesses a high energy density of 73.97 Wh kg?1 at a power density of 800 W kg?1, and maintain 22.01 Wh kg?1 at a high power density of 12.8 kW kg?1. These results demonstrate that hierarchical NiCoO2@Ni3S2 core/shell arrays have great potential as a positive electrode in supercapacitor with high energy density.

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