Multicomponent nitrogen-doped carbon@Ni-Co LDH nanosheet arrays as advanced electrode materials for supercapacitors

Abstract

Compositing nickel-cobalt layered double hydroxide (Ni-Co LDH) with special materials is a promising strategy to develop high-capacity electrode. But how to overcome the intrinsic defects of Ni-Co LDH by facile methods to obtain superior electrochemical performance is still a challenge. In this work, a multicomponent nitrogen-doped carbon@Ni-Co LDH (N/C@Ni-Co LDH) nanosheet arrays derived from zeolitic imidazolate framework is synthesized via a facile hydrothermal method, which provides three-dimensional open channels for the sufficient permeation of electrolyte. In addition, the N-doped carbon can enhance charge transfer capability and electrolytic accessibility. The N/C@Ni-Co LDH electrode exhibits an ultrahigh specific capacity of 405.5 mAh g−1 (2920 F g−1) at 1 A g−1. When it is served as the positive electrode in an asymmetric supercapacitor (ASC) of N/C@Ni-Co LDH//AC, the ASC reaches a high level of energy density (i.e. 93.6 Wh kg−1 at the power density of 1.75 kW kg−1) and excellent cycling stability (92.2% after 5000 cycles). This study demonstrates that the N/C@Ni-Co LDH is a promising candidate electrode material for the fabrication of high energy density supercapacitors.