Nickel-cobalt Double Hydroxide Research Articles

Synergistic coupling of NiCo-LDH in high-performance supercapacitors via hydrothermal method: Optimal utilization of the potential window

Enhancing the efficiency of layered nickel-cobalt double hydroxides (NiCo-LDH) as electrode materials represented a promising strategy for advancing supercapacitor technology and improving energy storage systems. However, achieving optimal synthesis conditions and addressing the inherent limitations of NiCo-LDH remained critical challenges. In this study, we developed a novel hydrothermal approach to fabricate ultrathin NiCo-LDH nanosheets with a highly porous architecture. In the present study, we have introduced a hydrothermal methodology aimed at the fabrication of ultrathin NiCo-LDH nanosheets characterized by an intricate and highly porous architecture. This innovative approach entailed the simultaneous deposition of nickel and cobalt hydroxides in the presence of ammonium fluoride, a technique that not only streamlined the synthesis process, but also markedly augmented the electrochemical performance of the resultant material. These effects collectively contributed to improved electron transport and structural stability. The optimized NiCo-LDH-18 electrode achieved an exceptional specific capacitance of 2266.6 F g⁻1 and an energy density of 104.8 W h kg⁻1, with a remarkable 93.19 % capacitance retention after 40,000 cycles. Additionally, the potential window of the system closely approximated its theoretical maximum, reaching 96.88 % at a current density of 10 A g⁻1. This refined synthesis strategy offered a significant advancement in supercapacitor performance and stability. By overcoming the inherent drawbacks of traditional supercapacitors, the developed materials provided an effective solution for meeting the growing demand for storage devices with high energy density.

Fabrication of Mildew-Resistant Wood with Multi-Functional Properties Based on In Situ Growth of Metal-Organic Frameworks.

Wood is easily affected by decay fungi, mildew fungi, insects, water, UV, and other factors when used outdoors. In particular, mildew on the surface of wood negatively affects the appearance and practical use of wood or wood-based engineered products. In recent years, as a class of popular crystalline materials, metal-organic frameworks (MOFs) have been widely applied in electrochemistry, adsorption, anti-mildew efforts, and other areas. In this study, we first grew a Co-based metal-organic framework (Co-MOF) in situ on a wood surface and subsequently converted the Co-MOF in situ into a cobalt-nickel double hydroxide layer, which formed micro- and nanohierarchical composite structures on the wood surface. The low surface energy of the CoNi-DH@wood was further modified via impregnation with sodium laurate to obtain the superhydrophobic wood (CoNi-DH-La@wood). We characterized the microstructure, chemical composition, water contact angle, and anti-mold properties of the CoNi-DH-La@wood using SEM, XRD, XPS, water contact angle tests, and anti-fungal tests. The SEM, XRD, and XPS results confirmed that the metal-organic framework was coated on the wood surface, with the long-chain sodium laurate grafted onto it. The CoNi-DH-La@wood had a water contact angle of 151°, demonstrating excellent self-cleaning ability. In addition, the fabricated superhydrophobic balsa wood exhibited excellent chemical and environment stability. Lastly, the CoNi-DH-La@wood exhibited excellent anti-mildew properties in a 30-day anti-mildew test because the superhydrophobic coating was successfully coated on the wood surface. In summary, this work presents an attractive strategy for obtaining wood with superhydrophobic properties at room temperature, thereby endowing the wood or wood-based engineered products with excellent anti-mildew properties.

Enhancing supercapacitor electrochemical performance through acetate-ion intercalation in layered nickel–cobalt double hydroxides

Enhancing the performance of layered nickel–cobalt double hydroxides (NiCo-LDH) as electrode materials for supercapacitors represents a promising strategy for optimizing energy storage systems. However, the complexity of the preparation method for electrode materials with enhanced electrochemical performance and the inherent defects of nickel–cobalt LDH remain formidable challenges. In this study, we synthesized acetate-ion-intercalated NiCo-LDH (NCLA) through a simple one-step hydrothermal method. The physical and chemical structural properties and supercapacitor characteristics of the as-prepared NCLA were systematically characterized. The results indicated that the introduction of Ac− engendered a distinctive tetragonal crystal structure in NiCo-LDH, concomitant with a reduced interlayer spacing, thus enhancing structural stability. Electrochemical measurements revealed that NCLA-8 exhibited a specific capacitance of 1032.2 F g−1 at a current density of 1 A g−1 and a high specific capacitance of 922 F g−1 at 10 A g−1, demonstrating a rate performance of 89.3%. Furthermore, NCLA-8 was used to construct the positive electrode of an asymmetric supercapacitor, while the negative electrode was composed of activated carbon. This configuration resulted in an energy density of 67.7 Wh kg−1 at a power density of 800 W kg−1. Remarkably, the asymmetric supercapacitor retained 82.8% of its initial capacitance following 3000 charge–discharge cycles at a current density of 10 A g−1. Thus, this study demonstrates the efficacy of acetate-ion intercalation in enhancing the electrochemical performance of NiCo-LDH, establishing it as a viable electrode material for supercapacitors.

Hierarchical Mo-doped Ni[sbnd]Co hydroxides cauliflower-like microspheres via a rapid microwave hydrothermal synthesis for supercapacitors

Transition metal double hydroxide (TMDH) materials have the advantages of low cost, simple preparation, wide variety, and tunable physical and chemical properties, which have broad research prospects in developing and applying high-performance electrode materials. Herein, molybdenum-doped nickel-cobalt double hydroxides (NiCoDH-Mo) were prepared by a rapid one-step microwave hydrothermal method in tens of minutes. Extensive investigations have been conducted on the morphology, crystal structure, and electrochemical properties of nickel‑cobalt double hydroxides with varying concentrations of Mo doping. The incorporation of Mo dopants into NiCoDH-Mo0.50 has yielded the formation of hierarchical cauliflower-like microspheres, which exhibit a significantly enhanced specific surface area of 91.7 m2 g−1 along with an improved electrical conductivity of 0.0233 μS cm−1. Thus, the optimized NiCoDH-Mo0.50 electrode has a high specific capacity of 160.5 mAh g−1 at a current density of 1 A g−1 and can maintain a high specific capacity of 115.3 mAh g−1 when the current density increases by 20 times. Finally, the NiCoDH-Mo cathode and mango seed-derived activated carbon anode were assembled into a hybrid supercapacitor with an energy density of 41.3 Wh kg−1 at a power density of 850 W kg−1, which also exhibits a capacity retention of 84 % after 8000 cycles. Therefore, we provide a facile and efficient strategy to prepare TMDH electrode materials with excellent performance for energy storage systems.

Improving the composite-structured supercapacitor assembled with Ni–Co-layered double hydroxide and polymer cement electrolyte through structural optimization

The optimized nickel–cobalt double hydroxide electrode by electrodeposition has a high specific area capacitance of 10.53 F cm−2. Capacitors assembled using the optimized electrodes have a specific capacitance of up to 1.442 F cm−2.

NiCo Prussian-Blue-Derived Cobalt–Nickel-Layered Double Hydroxide with High Electrochemical Performance for Supercapacitor Electrodes

High-performance electrode materials are crucial to the improvement of the supercapacitor performance index. Ni2Co1HCF@CoNi-LDH composites with a core–shell structure were prepared by a combination of coprecipitation and constant potential electrodeposition, and the microscopic morphology and phase composition of the composites were characterized by XRD, SEM, FTIR and XPS. The results showed that the NiCo Prussian blue (Ni2Co1HCF) was grown on the nickel foam (NF) substrate by in situ etching, while the nickel–cobalt double hydroxide (CoNi-LDH) was covered on the NiCo Prussian blue surface by electrodeposition, and the composite still retained the cubic skeleton morphology of the NiCo Prussian blue. The electrochemical properties of the composites were investigated using a three-electrode system in 2 M KOH. The results showed that their discharge specific capacity was as high as 1937 F·g−1 at a current density of 1 A·g−1 and still had 81.3% capacity retention at 10 A·g−1, and they exhibited an excellent rate capability. The capacity retention rate was 87.1% after 1000 cycles at 5 A·g−1 and, thus, the composite material has good application prospects as a supercapacitor electrode material.

Enhanced water electrolysis activity by CoNi-LDH/Co -nitrogen-doped carbon heterostructure with dual catalytic active sites

The study and development of bifunctional non-precious metal catalysts with excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) electrocatalytic activities are particularly important and challenging for electrocatalytic total water splitting. Here, we report a non-precious material constructed by growing cobalt-nickel double hydroxides on ZIF-derived Co nanoparticles and nitrogen-doped carbon framework (CoNi-LDH/Co@NC), which exhibits excellent electrocatalytic performances for both OER and HER in alkaline media. When used as OER and HER electrocatalysts, CoNi-LDH/Co@NC only needs 359 mV and 187 mV overpotentials at a current density of 100 mA cm−2, respectively. Surprisingly, using CoNi-LDH/Co@NC as both cathode and anode for a two-electrode water splitting system, a small battery voltage of 1.51 V is required at the current density of 10 mA cm−2, and the current density remained stable for 20 h without any obvious attenuation. This opens up new possibilities for further exploration of non-precious metal electrocatalysts for water splitting.

Electrochemically activated nickel-cobalt double hydroxide for aqueous ammonium-zinc hybrid battery

Electrochemically activated nickel-cobalt double hydroxide for aqueous ammonium-zinc hybrid battery

Facile assembly of cobalt-nickel double hydroxide nanoflakes on nitrogen-doped hollow carbon spheres for high performance asymmetric supercapacitors

Cobalt-nickel double hydroxide has high theoretical specific capacity and electrochemical activity but undergoes poor rate performance and cycle stability. Herein, cobalt-nickel double hydroxide/nitrogen-doped hollow carbon spheres (CoNi-DH/NHCS) hybrids with a hollow structure were fabricated via a simple deposition method at room temperature. Structural analysis confirmed that ultrathin CoNi-DH nanosheets with hydrotalcite structure were grown on the surface of NHCS. The presence of NHCS can adapt to volume changes during repeated charge-discharge procedures and improve stability. In addition, owing to the accelerated ions diffusion in the ultrathin nanosheets and improved conductivity, the electrode with a cobalt content of 15% presents the highest specific capacity (578 C g −1 at 1 A g −1 ) as well as brilliant rate capacity (76.54%, 1–20 A g −1 ). The all-solid-state asymmetric supercapacitor 15CoNi-DH/NHCS‖NHCS depicts a superior energy density of 27.51 Wh kg −1 at 800 W kg −1 as well as distinguished cycle stability of 91.65% reservation after 10000 cycles. • CoNi-DH/NHCS hybrids were obtained by a facile deposition method. • The hollow structure can adapt to volume changes during charge-discharge procedure. • A specific capacity of 578 C g −1 was obtained for the CoNi-DH/NHCS at 1 A/g. • The asymmetric supercapacitor delivers high stability of 91.65% after 10,000 cycles.

Well-assembled nanosheets of nickel-cobalt double hydroxide flower as a reversible faradic battery-type electrode material for high-performance hybrid supercapacitor

The design and advancement of the interconnected three-dimensional (3D) porous nanoarchitecture electrode materials with fascinating electrochemical performance are in high demand for high-performance hybrid supercapacitors (HSCs). Herein, we report a facile fabrication of 3D flower-like nickel-cobalt double hydroxides (NiCoDH) architecture via a template-free hydrothermal approach. The NiCoDH flower-like architecture is composed of self-assembling and interconnecting many thin nanosheets with thicknesses ranging from 11–16 nm. The open void space and vertically oriented nanosheets in the NiCoDH flower-like architecture could shorten the pathway for the charge and electrons transport and offer abundant electroactive sites for redox reactions to enhance the electrochemical performance of the electrode material. The flower-like NiCoDH electrode material reveals a high specific capacity (Qs) of 731 C g−1 at the current of 1 A g−1 and retains 461 C g−1 even at 20 A g−1, signifying the high rate capability of the obtained electrode material. The HSC is constructed by adopting the NiCoDH and activated carbon (AC) as the positrode and negatrode, respectively. Further, the HSC supplies a Qs of 352 C g−1, and it offers a high energy density of 58.30 Wh kg−1 at the power density of 21.09 kW kg−1 and an excellent long-term cyclic life (∼90.4% retention over 10,000 repeated GCD cycles).

Fabrication of flexible, binder-free, and self-standing nickel cobalt double hydroxide/graphene films for advanced alkaline batteries

Rechargeable alkaline Ni-Zn batteries possess high promising in large-scale energy storage systems, and wearable flexible devices due to their low cost, high safety, and high energy density compared with other aqueous batteries. However, the traditional preparation method together with the use of bulky Ni mesh current collector has limited their applications. Herein, a simple dry pressing process without the using of any organic solvents is developed to prepare Binder-free, flexible, and lightweight Nickel Cobalt double hydroxide (NiCo-DH) based films, NiCo-DH/GNP@rGO, where NiCo-DH is prepared as active material, graphene nanoplatelets powder (GNP) is used as both conductive and supporting frame, and reduced graphene oxide (rGO) is coated as protective layer of the films. Areal mass of the flexible film is only about 4.2 mg cm−2, and mass loading of NiCo-DH is about 33%. In a three-electrode system, the NiCo-DH/GNP@rGO delivers a high specific capacity of 213 mAh g−1, and outstanding cycling performance (88.8% capacity retention after 1000 cycles’ running at 1 A g−1). Assembled into a full cell using Zn foil as anode, a discharge voltage of 1.6 V is realized. The flexible films prepared here exhibit a promising application prospect in portable and wearable electronic devices.

Branch-cell shape liked nickel-cobalt layer double hydroxides composite polypyrrole for high performance supercapacitor

Branch-cell shape liked nickel-cobalt layer double hydroxides composite polypyrrole for high performance supercapacitor

Zinc-induced phase reconstruction of cobalt–nickel double hydroxide cathodes for high-stability and high-rate nickel–zinc batteries

Nickel–zinc (Ni–Zn) batteries have received extensive attention in the field of energy storage. However, the unsatisfactory durability greatly impedes their wider commercial application. Herein, a novel and efficient zinc-induced phase reconstruction method was reported to boost the electrochemical stability of cobalt–nickel double hydroxide (CoNi-DH) cathode materials for developing high-stability and high-rate Ni–Zn batteries. The inherent mechanism for this phase reconstruction method to achieve the improvement of electrochemical stability was systematically investigated and clarified in this work by combining theoretical calculations and experimental tests. The research results confirmed that the zinc-induced phase reconstruction can produce a new phase of Zn2Co3(OH)10·2H2O in the mixed-phase of CoNi-DH without sacrificing its hierarchical micro-nano structure. This Zn2Co3(OH)10·2H2O phase has a much smaller shrinkage of the lattice spacing of host layers during the redox reaction relative to the pure Co(OH)2 phase, thereby it can inhibit structural damage during the charge–discharge cycle. In addition, the retained hierarchical micro-nano structure can ensure good capacity output. Therefore, the as-fabricated mixed hydroxide electrode and Ni–Zn battery achieve remarkable improvement in the cycling life and exhibit superior rate performance. Moreover, the resultant mixed hydroxide electrode displays good application in the flexible quasi-solid-state Ni-Zn battery.

Template-directed growth of ordered metal-organic frameworks array and derived nickel-cobalt double hydroxide electrode for hybrid supercapacitor and aqueous NiCo-Zn battery

Rational design of self-supporting and well-aligned MOF-derived electrode materials is a great challenge. In this work, we report a novel strategy for preparing nickel-cobalt double hydroxide (NiCo-DH) array on nickel foam with template-directed growth of MOF array as the precursor. The obtained sample can be directly applied to both Ni-Zn aqueous secondary battery and hybrid supercapacitor. Due to the many advantages inherited from the MOFs material, the NiCo-DH array displays an ultrahigh reversible specific capacitance (325.6 mAh g−1 at 2 mA cm−2) and excellent rate performance (75.5% of initial capacity retention under 40 mA cm−2). As a cathode for NiCo-Zn batteries, the NiCo-DH electrode exhibits a high specific capacity of 329 mAh g−1 and satisfactory cycling stability. Moreover, the assembled NiCo-DH //active carbon asymmetric supercapacitor exhibited a remarkable capacity of 0.359 mAh cm−1 at 0.5 mA cm−1 and exhibited excellent durability (capacitance retention of 91% after 5 000 cycles). Furthermore, the hybrid device exhibited an impressive energy density of 50.5 Wh kg−1 at a power density of 750 W kg−1. The presented strategy for controlled design and synthesis of MOF-derived self-supported electrode offers prospects in developing highly electrochemical active electrode materials in energy storage devices.

Hierarchical Cobalt‐Nickel Double Hydroxide Arrays Assembled on Naturally Sedimented Ti3C2Tx for High‐Performance Flexible Supercapacitors

AbstractFlexible electrodes with excellent energy storage and conversion properties that can be produced by a simple process are highly desirable for supercapacitors. Herein, Cobalt‐Nickel double hydroxide (CoNi‐DH) micro‐nanosheet arrays are prepared uniformly on naturally sedimented Ti3C2Tx films by an etching‐deposition‐growth process to form a CoNi‐DH@Ti3C2Tx heterostructure. The naturally sedimented Ti3C2Tx film serves as the substrate to minimize aggregation of the CoNi‐DH nanoarrays to enhance the electrical conductivity. Furthermore, the hierarchical structure comprised of the CoNi‐DH interconnected nanoarrays promotes electrolyte access. By taking advantage of the excellent electrical conduction and high theoretical specific capacitance, the flexible CoNi‐DH@Ti3C2Tx electrode in the supercapacitor delivers a superior specific capacitance of 919.5 F g−1 at 1 A g−1, and remarkable capacitance retention of 89.6% after 5000 cycles at 20 A g−1. Density‐functional theory calculations are performed to investigate the charge density difference and partial density of states of CoNi‐DH@Ti3C2Tx and the theoretical assessment suggests that the chemical bonds between Ti3C2Tx and CoNi‐DH are critical to the charge transport, electrical conductivity, and structural stability.

In Situ Transformation of Metal-Organic Frameworks into Hollow Nickel-Cobalt Double Hydroxide Arrays for Efficient Water Oxidation.

Developing earth-abundant electrocatalysts for efficient oxygen evolution reaction (OER) is of paramount significance for electrochemical water splitting. Herein, an efficient in situ etching-deposition growth strategy is employed to transform pristine two-dimensional (2D) Co-metal-organic frameworks into hollow Ni/Co double hydroxide arrays (denoted as Ni/Co-DH), which not only yields a larger surface area and exposes more active sites but also decreases the activation energy to the OER. With structural and compositional benefits, the Ni/Co-DH exhibits high performance with an overpotential of 229 mV at 10 mA cm-2 and exceptional long-term stability of over 90 h in 1 M KOH medium for OER, comparable to most non-noble oxygen evolution catalysts reported so far. In addition, a two-electrode Ni/Co-DH∥Pt/C electrolyzer also requires a considerably low voltage of 1.58 V at 10 mA cm-2 for overall water splitting. This study affords a rational strategy to develop water-alkali electrolyzers with great complexity for large-scale water-splitting systems.

2D layered nickel-cobalt double hydroxide nano sheets @ 1D silver nanowire-graphitic carbon nitrides for high performance super capacitors

Designing nanostructured electrocatalysts plays an important role in improving the electro-catalytic behaviors of energy storage devices. Achieving the high specific capacitance of these devices depends on the structure of nanomaterials and their synthesis process. Herein, we report a novel system consisting of 2D layered materials and 1D nanowire with desirable properties suitable for supercapacitor applications. Nickel-Cobalt layered double hydroxide (Ni-Co LDH)@Silver nanowire (Ag NWs)/graphitic carbon nitride (g-C3N4) nanomaterial was successfully synthesized using hydrothermal and ultra-sonication methods. The structural studies of the synthesized Ni-Co LDH based electrode materials are characterized by using different analytical techniques namely, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FE-SEM), High-resolution transmission electron microscopy (HR-TEM), Energy dispersive spectroscopy (EDAX). The electrochemical performance of Ni-Co LDH@Ag NWs/g-C3N4 hybrid electrode is investigated using Galvanostatic charge-discharge (GCD), cyclic and voltammetry (CV) techniques. The designed 3D nanostructured composites (Ni-Co LDH@Ag NWs/g-C3N4) showed high specific capacitance of 848.5 F/g at a current density at 1 A/g as good cyclic stability after 2000 cycles charge-discharge duration (93.5% at current density 5 A/g).

Dispersed nickel-cobalt double metal hydroxide self-assembled with polystyrene sulfonic acid polyelectrolyte for the preparation of carbon solid solid supercapacitors with wide temperature range and long cycle stability

Although polyelectrolytes with good electrochemical compatibility have been widely used in all solid-state supercapacitors, the random dispersion of polymer chains results in a narrow operating temperature range, which limits its further application. Herein, through the electrostatic attraction assembly strategy, the negatively charged polystyrene sulfonic acid (PSS) and the positively charged layered nickel-cobalt double hydroxide (NiCo-LDH) nanosheets are synthesized into PSS/NiCo-LDH composite electrolyte. Meanwhile, the polyelectrolyte shows a wide temperature application range (20–80 °C) and excellent electrochemical cycle stability in solid supercapacitor (capacitance retention rate reaches 96.2% after 5000 cycles) based on activated-carbon electrodes. The remarkable thermal stability and electrochemical performance are mainly attributed to the addition of NiCo-LDH, which is not only limit the thermal decomposition of PSS molecular chains, but also accelerate the migration rate of electrolyte ions. This work opens a way for the preparation of polyelectrolyte with wide temperature range and long cycle stability for application in solid-state supercapacitors.

Hollow C-LDH/Co9S8 nanocages derived from ZIF-67-C for high- performance asymmetric supercapacitors

The design of supercapacitor electrode materials greatly depends on the rational construction of nanostructures and the effective combination of different active materials. Due to the poor electrical conductivity and mechanical strength, nickel-cobalt double hydroxide (NiCo-LDH) cannot reach the theoretical high specific capacitance value, while Co9S8 shows many interesting features, such as excellent electrochemical properties, high conductivity, and greatly improved redox reactions. Therefore, we prepared ZIF-67-C derived hollow NiCo-LDH (C-LDH)/Co9S8 nanocages containing two components of Co9S8 and NiCo-LDH through a multistep transformation method. The prepared C-LDH/Co9S8 nanoparticles showed a hollow rhomboid dodecahedron structure, and many NiCo-LDH nanosheets were reasonably distributed on the surface. In the three-electrode test, it can be obtained that its specific capacitance is 1654 F·g−1 when current density is 2 A·g−1 and 82.5% capacitance retention after 5000 cycles. Moreover, asymmetric supercapacitors (ASCs) prepared with C-LDH/Co9S8 as cathode and AC as anode can achieve a large energy density of 47.3 Wh·kg−1 under the condition of high power density of 1505 W·kg−1. After 10,000 cycles, capacitance retention rate is 80.9%, exhibit excellent cycle performance, suggesting the great potential of hollow C-LDH/Co9S8 nanocages in the application of supercapacitors.

Electrodeposition of Ultrathin Nanosheets of Nickel-Cobalt Double Hydroxides with Layered Structure for Improved Supercapacitor Performance

Electrodeposition of Ultrathin Nanosheets of Nickel-Cobalt Double Hydroxides with Layered Structure for Improved Supercapacitor Performance