Battery-like supercapacitive behavior of urchin-shaped NiCo₂O₄ and comparison with NiCo₂X₄ (X = S, Se, Te)

Abstract

Bimetallic chalcogenides are promising as potential electrode materials for supercapacitors on account of their multiple oxidation states and better electroactivity. Anion effect on the electrochemical performance of urchin-shaped NiCo2X4, (X = O, S, Se, Te) is reported here. These materials crystallize in spinel cubic and monoclinic phases. Electron micrographs show that the materials possess a nanorod-like morphology that protrude from surfaces of microspheres. This gives it urchin-like appearance. Their structure enables ion permeability allowing for improved charge-discharge kinetics. The specific capacities obtained from 3-electrode electrochemical cell measurements are 137 mAh g-1 (492 C g-1), 108 mAh g-1 (390 C g-1), 76 mAh g-1 (272 C g-1) and 72 mAh g-1 (258 C g-1), respectively, for NiCo2O4, NiCo2S4, NiCo2Se4, and NiCo2Te4 at 2 A g-1. An asymmetric Swagelok device is fabricated for each chalcogenide material. Due to well-defined morphology and sufficient specific surface area, NiCo2O4 proved to be the best material delivering a maximum energy density of 34 Wh kg-1 and power density of 6 kW kg-1 followed by NiCo2Te4 delivering 22 Wh kg-1 and 11.25 kW kg-1. Higher electrical conductivity of the telluride-based materials makes them efficient supercapacitor electrodes. Selenium-based materials display better cyclic stability owing to the monoclinic phase

Ribbon-like Nickel Cobaltite with Layer-by-Layer-Assembled Ordered Nanocrystallites for Next-Generation All-Solid-State Hybrid Supercapatteries

“…Physicochemical Analyses of the NiCo 2 O 4 . To know about the crystal lattice planes and crystallinity of the material, PXRD analysis was performed, and Figure 1A shows the PXRD pattern of the material, showing various diffraction peaks at 2θ values of 18,31,36,38,44,55,59, 64, and 77°, which are ascribed to the (111), (220), (311), ( 222), (400), (422), (511), (440), and (533) lattice planes of FCC NiCo 2 O 4 (JCPDS no. : 01-073-1702).…”

“…The charge storage efficiency of the ribbon-like NiCo 2 O 4 is significantly more than the very recently reported urchin-like NiCo 2 O 4 and the reported other NiCo 2 O 4 -based electrode materials. 18 As NiCo 2 O 4 is comprehensively porous, usually, two different types of capacitive charge storage, that is, diffusion capacitance and surface capacitance, may possibly contribute to the overall charge storage of the material. 11 In order to analyze the mechanism of charge storage in NiCo 2 O 4 , the relationship between i and ν is investigated using eqs 3 and 4.…”

“…3,16,17 One very recent report by Aparna et al also shows that among various Ni-and Co-based chalcogenides, that are, oxides, sulfides, selenides, and tellurides, spinel NiCo 2 O 4 is most efficient for supercapacitive energy storage. 18 Contextually, numerous micro/nanostructurally, pore architecturally, and electronically tuned nickel cobaltite electrode materials have been developed, which are found to offer enhanced charge storage efficiencies, when employed as redox-based electrode materials in supercapacitors/supercapatteries. 18−22 In this prospect, crystallites with reduced dimension and ordered arrangements produce materials with enhanced active surface area, systematic pore architecture, additional intrinsic porosity, augmented active surface accessibility, and improved electronic conductivity.…”

“…20,26,27 This also results in poor electrochemical energy storage efficiency of the nickel cobaltite-based electrode materials and unfeasible long-term working stability of the corresponding supercapacitor/supercapattery devices. 18 In this context, comprehensive designing of lower dimensional nickel cobaltite electrode materials with uniform nanoscale crystallites and ordered arrangement is the essential need of the time in order to develop next-generation high-performance supercapatteries. Fundamentally, retarded kinetics during the crystal growth in the presence of precise surface deactivators helps in the growth of crystallites with tuned dimension and systematic arrangement, which essentially leads to materials with lower surface energy and higher microstructural uniformity.…”

Recent advances in various applications of nickel cobalt sulfide-based materials

“…6e). 105 It means that the reaction kinetics of NCSs in the charge storage processes are partially determined by the diffusion-controlled redox behavior ( i.e. , , where I is the current and v is the scan rate in CVs), while the reaction kinetics of pseudocapacitance are dominated by the surface-controlled faradaic process ( i.e.…”