Controllable Morphology of Sea-Urchin-like Nickel–Cobalt Carbonate Hydroxide as a Supercapacitor Electrode with Battery-like Behavior

Abstract

Nickel–cobalt carbonate hydroxide with a three-dimensional (3D) sea-urchin-like structure was successfully developed by the hydrothermal process. The obtained structure enables the enhancement of charge/ion diffusion for the high-performance supercapacitor electrodes. The mole ratio of nickel to cobalt plays a vital role in the densely packed sea-urchin-like structure formation and electrochemical properties. At optimized nickel/cobalt mole ratio (1:2), the highest specific capacitance of 950.2 F g–1 at 1 A g–1 and the excellent cycling stability of 178.3% after 3000 charging/discharging cycles at 40 mV s–1 are achieved. This nickel–cobalt carbonate hydroxide electrode yields an energy density in the range of 42.9–15.8 Wh kg–1, with power density in the range of 285.0–2849.9 W kg–1. The charge/discharge mechanism at the atomic level as monitored by time-resolved X-ray absorption spectroscopy (TR-XAS) indicates that the high capacitance behavior in a nickel–cobalt carbonate hydroxide is mainly dominated by cobalt carbonate hydroxide.

Two-Dimensional Synergistic Interfacial Orientation on Tin Oxide-Reinforced Cobalt Carbonate Hydroxide Heterostructures for High-Performance Energy Storage

“…The urea molecules play a crucial part in promoting a growth-directing agent that influences the crystalline nature and allows for the inclusion of interlayer CO 3 2– ions. The corresponding reaction − occurs in the CED process as an electric current flow through the electrolyte − CO false( normalN H 2 false) 2 + 3 H 2 normalO → normalC O 2 + 2 normalO H − + 2 false( normalN H 4 false) + normalC O 2 + H 2 normalO → normalC O 3 2 − + 2 H + normalC o 2 + + normalC O 3 2 − + 2 normalO H − → Co ( C normalO 3 ) false( OH false) 2 …”

Are Fractal-Like Structures Beneficial for Supercapacitor Applications? A Case Study on Fe2O3 Negative Electrodes

“…42 The plateaus in GCDs (at 1 A g −1 ) represent batterylike (diffusive) behavior during charge storage by these electrodes, consistent with the appearance in both faradaic features in CVs (peaks in Figure 5a,c,e). 43 The specific capacitance (C sp ) was estimated by considering the discharge segment of GCD data by considering its whole duration at any current density. However, for representation purposes, the GCDs are shown up to only shorter durations in Figure 5b,d,f to render the plateaus visible.…”

“…This is mainly due to the surface adsorption of the charge, consistent with CVs (Figure a,c,e) . The plateaus in GCDs (at 1 A g –1 ) represent battery-like (diffusive) behavior during charge storage by these electrodes, consistent with the appearance in both faradaic features in CVs (peaks in Figure a,c,e) . The specific capacitance ( C sp ) was estimated by considering the discharge segment of GCD data by considering its whole duration at any current density.…”

MOF-Derived Nickel–Cobalt Sulfide Nanoflakes Wrapped Carbon Nanotubes for Hybrid Supercapacitors

“…3−7 Among them, due to the effective synergistic effect between nickel and cobalt, nickel−cobalt-based binary metal sulfide has abundant active sites and high redox activity, which makes it have considerable potential in the application of supercapacitors. 8−12 To further enhance the overall performance, bimetallic sulfides with various morphologies were synthesized as electrode materials, such as rambutan-like, 13 nanosheets, 14,15 nanoflowers, 16,17 urchin-like, 18,19 etc. In recent years, metal− organic framework (MOF) materials have been regarded as the optimal precursor materials for bimetallic sulfides due to their controllable structure and abundant porosity.…”

“…A supercapacitor is a new type of energy storage device, which has the advantages of high energy density, high power density, and fast charging and discharging. In order to better satisfy the actual demand, researchers have been aiming at developing superior electrode materials to improve the electrochemical performance of supercapacitors. , Due to the low electronegativity and high electrochemical activity, transition metal compounds have excellent electron transfer efficiency and rapid redox reaction during charge and discharge, which has led to their considerable attention in energy storage. − Among them, due to the effective synergistic effect between nickel and cobalt, nickel–cobalt-based binary metal sulfide has abundant active sites and high redox activity, which makes it have considerable potential in the application of supercapacitors. − To further enhance the overall performance, bimetallic sulfides with various morphologies were synthesized as electrode materials, such as rambutan-like, nanosheets, , nanoflowers, , urchin-like, , etc. In recent years, metal–organic framework (MOF) materials have been regarded as the optimal precursor materials for bimetallic sulfides due to their controllable structure and abundant porosity. − …”