Synthesis of CNT@CoS/NiCo Layered Double Hydroxides with Hollow Nanocages to Enhance Supercapacitors Performance

Abstract

One of the key factors to improve electrochemical properties is to find exceptional electrode materials. In this work, the nickel-cobalt layered double hydroxide (CNT@CoS/NiCo-LDH) with the structure of a hollow nanocage was prepared by etching CNT@CoS with zeolitic imidazolate framework-67 (ZIF-67) as a template. The results show that the addition of nickel has a great influence on the structure, morphology and chemical properties of materials. The prepared material CNT@CoS/NiCo-LDH-100 (C@CS/NCL-100) inherited the rhombic dodecahedral shape of ZIF-67 well and the CNTs were evenly interspersed among the rhombic dodecahedrons. The presence of CNTs improved the conductivity and surface area of the samples. The C@CS/NCL-100 demonstrates a high specific capacitance of 2794.6 F g−1 at 1 A g−1. Furthermore, as an assemble device, the device of C@CS/NCL-100 as a positive electrode exhibits a relatively high-energy density of 35.64 Wh kg−1 at a power density of 750 W kg−1 Further, even at the high-power density of 3750 W kg−1, the energy density can still retain 26.38 Wh kg−1. Hence, the superior performance of C@CS/NCL-100 can be ascribed to the synergy among CNTs, CoS and NiCo LDH, as well as the excellent three-dimensional structure obtained by used ZIF-67 as a template.

MOF-Derived Ultrathin NiCo-S Nanosheet Hybrid Array Electrodes Prepared on Nickel Foam for High-Performance Supercapacitors

“…The two pairs of diffraction peaks and satellite peaks indicated two different valence states of Co atoms in NiCo-S, Co 2+ , and Co 3+ , respectively [ 38 ]. In Figure 3 d, the peaks at 163.8 and 162.27 eV in the S 2p spectra could be attributed to S 2p 1/2 and S 2p 3/2 , respectively, indicating that the S atom in the sample material was S 2− [ 28 ]. Meanwhile, another peak at 168.65 eV could be assigned to the high-valence oxidation peaks of surface sulfur pieces.…”

“…Therefore, increasing the specific surface area of bimetallic sulfide by adjusting its morphology for enhanced electrochemical performance is essential. Metal–organic framework (MOF) is a porous crystal structure formed by the orderly connection of metal central sites and organic ligands, and it presents the characteristics of high specific surface area [ 27 , 28 ]. Transition metal compounds derived from MOF as a sacrificed template could inherit the excellent properties of MOF.…”

Porous NiMoO4-NrGO as a Battery-Like Electrode Material for Aqueous Hybrid Supercapacitors

“…In addition, the slope of the linear part of the NMO-NrGO//AC impedance curve before the cycling performance is almost vertical. This indicates lower Warberg resistance (Z W ) and better capacitive behavior before the cycling testing [57]. Z W is related to the diffusion rate of the OH − ions intercalating to the electrode.…”