Layered Double Hydroxide Electrode Research Articles

Investigation of the Electrochemical Properties of CoAl-Layered Double Hydroxide/Ni(OH)2

Layered double hydroxides (LDH) as active electrode materials have become the focus of research in energy storage applications. The manufacturing of excellent electrochemical performance of the LDH electrode is still a challenge. In this paper, the production of CoAl-LDH@Ni(OH)2 is carried out in two steps, including hydrothermal and electrodeposition techniques. The prominent features of this electrode material are shown in the structural and morphological aspects, and the electrochemical properties are investigated by improving the conductivity and cycle stability. The core of this experimental study is to investigate the properties of the materials by depositing different amounts of nickel hydroxide and changing the loading of the active materials. The experimental results show that the specific capacity is 1810.5F·g−1 at 2 A/g current density and the cycle stability remained at 76% at 30 A g−1 for 3000 cycles. Moreover, a solid-state asymmetric supercapacitor with CoAl-LDH@Ni(OH)2 as the positive electrode and multi-walled carbon nanotube coated on the nickel foam as the negative electrode delivers high energy density (16.72 Wh kg−1 at the power density of 350.01 W kg−1). This study indicates the advantages of the design and synthesis of layered double hydroxides, a composite with excellent electrochemical properties that has potential applications in energy storage.

Design and synthesis of Ni-Co and Ni-Mn layered double hydroxides hollow microspheres for supercapacitor

The development of electrode materials with hierarchically porous structure and high electrochemical stability is crucial for the electric energy density of supercapacitors. Hollow microspheres of Ni-Co layered double hydroxides (LDHs) and Ni-Mn LDHs are fabricated with a simple co-precipitation method at low temperature using SiO2 microspheres as a sacrifice template. The as-fabricated two LDH hollow microspheres possess a unique 3D architecture and exhibit high specific capacitance, as well as excellent rate and cycling performances as electrode materials of supercapacitors. A specific capacitance of 1766.4 F g−1 at 1 A g−1 is achieved for Ni-Co LDHs electrode, much higher than that of Ni-Mn LDHs. A hybrid capacitor composed of Ni-Co LDHs hollow spheres and activated carbon is fabricated and evaluated for practical application, providing an energy density of 44.3 Wh kg−1 at a power density of 0.425 kW kg−1. This study indicates that the hollow LDH microsphere prepared by our method is a promising material for supercapacitors.

NiCo2S4/Ni–Co layered double hydroxide nanocomposite prepared by a vapor-phase hydrothermal method for electrochemical capacitor application

Abstract In this work, NiCo 2 S 4 /Ni–Co layered double hydroxide (LDH) nanocomposites were prepared by using Ni–Co LDH nanosheets as precursor through a vapor-phase hydrothermal method. The NiCo 2 S 4 /Ni–Co LDH nanocomposites have a hierarchical structure in which interconnected NiCo 2 S 4 nanosheets with smaller sizes are loaded on Ni–Co LDH nanosheets. Electrochemical performances of the NiCo 2 S 4 /Ni–Co LDH nanocomposites were measured by cyclic voltammetry and galvanostatic charge–discharge techniques. The NiCo 2 S 4 /Ni–Co LDH electrode achieved a capacity of 1765 F g −1 at 1 A g −1 and a capacity of 940 F g −1 at 10 A g −1 . Control experiments showed that the capacities of the NiCo 2 S 4 /Ni–Co LDH are higher than Ni–Co LDH and NiCo 2 S 4 nanosheets. The better electrochemical performances of the NiCo 2 S 4 /Ni–Co LDH electrode can be attributed to the unique hierarchical structure which was formed during the vapor-phase hydrothermal process.

High-Performance Hybrid Supercapacitor with 3D Hierarchical Porous Flower-like Layered Double Hydroxide Grown on Nickel Foam As Binder-Free Electrode

The synthesis of layered double hydroxide (LDH) as electroactive material has been well reported; however, fabricating an LDH electrode with excellent electrochemical performance at high current density remains a challenge. In this paper, we report a 3D hierarchical porous flower-like NiAl-LDH grown on nickel foam (NF) through a liquid-phase deposition method as a high-performance binder-free electrode for energy storage. With large ion-accessible surface area as well as efficient electron and ion transport pathways, the prepared LDH-NF electrode achieves high specific capacity (1250 C g-1 at 2 A g-1 and 401 C g-1 at 50 A g-1) after 5000 cycles of activation at 20 A g-1 and high cycling stability (76.7% retention after another 5000 cycles at 50 A g-1), which is higher than those of most previously reported NiAl-LDH-based materials. Moreover, a hybrid supercapacitor with LDH-NF as the positive electrode and porous graphene nanosheet coated on NF (GNS-NF) as the negative electrode, delivers high energy density (30.2 Wh kg-1 at a power density of 800 W kg-1) and long cycle life, which outperforms the other devices reported in the literature. This study shows that the prepared LDH-NF electrode offers great potential in energy storage device applications. Figure 1

Layered double hydroxide materials coated carbon electrode: New challenge to future electrochemical power devices

Layered double hydroxides (LDHs) have been widely used in the past years due to their unique physicochemical properties and promising applications in electroanalytical chemistry. The present paper is going to focus exclusively on magnesium-aluminum and zinc-aluminum layered double hydroxides (MgAl & ZnAl LDHs) in order to investigate the property and structure of active cation sites located within the layer structure. The MgAl and ZnAl LDH nanosheets were prepared by the constant pH co-precipitation method and uniformly supported on carbon-based electrode materials to fabricate an LDH electrode. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy revealed the LDH form and well-crystallized materials. Wetting surface properties (hydrophilicity and hydrophobicity) of both prepared LDHs were recorded by contact angle measurement show hydrophilic character and basic property. The electrochemical performance of these hybrid materials was investigated by mainly cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry techniques to identify the oxidation/reduction processes at the electrode/electrolyte interface and the effect of the divalent metal cations in total reactivity. The hierarchy of the modified electrode proves that the electronic conductivity of the bulk material is considerably dependent on the divalent cation and affects the limiting parameter of the overall redox process. However, MgAl LDH shows better performance than ZnAl LDH, due to the presence of magnesium cations in the layers. Following the structural, morphological and electrochemical behavior studies of both synthesized LDHs, the prepared LDH modified electrodes were tested through microbial fuel cell configuration, revealing a remarkable, potential new pathway for high-performance and cost-effective electrode use in electrochemical power devices.

High-performance hybrid supercapacitor with 3D hierarchical porous flower-like layered double hydroxide grown on nickel foam as binder-free electrode

The synthesis of layered double hydroxide (LDH) as electroactive material has been well reported; however, fabricating an LDH electrode with excellent electrochemical performance at high current density remains a challenge. In this paper, we report a 3D hierarchical porous flower-like NiAl-LDH grown on nickel foam (NF) through a liquid-phase deposition method as a high-performance binder-free electrode for energy storage. With large ion-accessible surface area as well as efficient electron and ion transport pathways, the prepared LDH-NF electrode achieves high specific capacity (1250 C g−1 at 2 A g−1 and 401 C g−1 at 50 A g−1) after 5000 cycles of activation at 20 A g−1 and high cycling stability (76.7% retention after another 5000 cycles at 50 A g−1), which is higher than those of most previously reported NiAl-LDH-based materials. Moreover, a hybrid supercapacitor with LDH-NF as the positive electrode and porous graphene nanosheet coated on NF (GNS-NF) as the negative electrode, delivers high energy density (30.2 Wh kg−1 at a power density of 800 W kg−1) and long cycle life, which outperforms the other devices reported in the literature. This study shows that the prepared LDH-NF electrode offers great potential in energy storage device applications.

Urea biosensor based on Zn 3Al–Urease layered double hydroxides nanohybrid coated on insulated silicon structures

Urea biosensors for medical diagnostic monitoring were developed based on the immobilization of urease within layered double hydroxides (LDH). The urease–LDH material was obtained by a stepwise exchange reaction by urease of a Zn 3Al–dodecyl sulphate (ZnAl–DS) colloidal suspension. XR diffraction and FTIR analysis show that this method gives rise to a Zn 3Al–Urease LDH nanohybrid material with urease dispersion and textural properties. An aqueous suspension of this urease–LDH nanohybrid material was deposited on an insulated semiconductor (IS) structure. Biosensor responses to urea additions were obtained using capacitance ( C vs. V) and impedance ( Z vs. ω) measurements. An enhanced maximum limit of the dynamic range was observed in the case of the impedance measurements (110 mM) compared to (5.6 mM) the capacitive urea biosensor. The Michaelis–Menten constant was also calculated according to the Lineweaver–Burk plot. It was found that the K m value with immobilized enzymes was lower ( K m = 0.67 mM) in comparison with free enzymes. This K m value obtained from the capacitance measurements indicates that the urea degradation is performed within any inhibition action on the IS/Zn 3Al–Urease LDH electrode. A comparative study was carried out between these results and those obtained previously, using urease/ZnAl–Cl layered double hydroxides mixture coated on the pH-ISFET transducer.