The nickel hydroxide nanopowders mixed with SnO2 nanoparticles as an additive in different proportions were prepared and characterised by X-ray diffraction (XRD), transmission electron microscope (TEM) and electrochemical measurement by cyclic voltammetry. XRD examination suggests that the composite Ni(OH)2/SnO2 has both the phases of α-Ni(OH)2 and β-Ni(OH)2 with SnO2 nanoparticles. TEM images show the nanostructures of nickel hydroxide, SnO2 and dispersion of SnO2 nanoparticles on nickel hydroxide particles in the composite. The electrochemical studies revealed that the composite electrode has better redox reversibility and specific capacitance values compared to the pure Ni(OH)2, α-Ni(OH)2 and usual β-Ni(OH)2 electrodes and it can be applied as a promising positive active material for alkaline rechargeable batteries. 相似文献
A Ni(OH)2 composite with good electrochemical performances was prepared by a facile method. Ni(OH)2 was homogeneously grown on the hydrophilic graphene/graphene oxide (G/GO) nanosheets, which can be prepared in large scale in my lab. Then G/GO/Ni(OH)2 was reduced by L-Ascorbic acid to obtain G/RGO/Ni(OH)2. Caused by the synergy effects among the components, the G/RGO/Ni(OH)2 electrode showed good electrochemical properties. The G/RGO/Ni(OH)2 electrode possessed a specific capacitance as high as 1510 F g−1 at 2 A g−1 and even 890 F g−1 at 40 A g−1. An asymmetric supercapacitor device consisting of G/RGO/Ni(OH)2 and reduced graphene oxide (RGO) was installed and displayed a high energy density of 44.9 W h kg−1 at the power energy density of 400.1 W kg−1. It was verified that the G/GO nanosheets are ideal supporting material in supercapacitor. 相似文献
Immobilization of redox species like Ni(OH)2 onto the electrode surface is important in the application areas such as super capacitor, electrochromic displays and electrocatalysis. Nickel hexacyanoferrate (NiHCF) modified glassy carbon could be further derivatized with Ni(OH)2 by electrochemical cycling in alkali. The electrodeposition of Ni(OH)2 was usually carried out onto the electrode surface from nickel salt at high interfacial pH. This paper reports the preparation of Ni(OH)2 from insoluble nickel tetracyanonickelate supported on carbon (NTN/C). This insoluble precursor complex was decomposed by two methods. (1) By potential cycling of modified electrode with the above complex in alkali. (2) By thermal decomposition of the precursor complex (NTN/C) to form metallic nickel followed by cycling in alkali. Ni(OH)2 modified electrodes formed using both methods were characterized by cyclic voltammetry and also by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Further, electrocatalytic properties of Ni(OH)2/C modified electrodes formed by the above two methods were studied and compared using borohydride oxidation as probe reaction. 相似文献
Nickel hydroxide consisting of loosely packed nanospheres was synthesized as positive electrode material for an asymmetric capacitor based on Ni(OH)2 and activated carbon (AC). Two series of supercapacitors were fabricated to investigate the effects of the single electrodes of Ni(OH)2 and AC on the electrochemical performance of asymmetric Ni(OH)2–AC capacitor. Parameters including cell voltage window, specific capacitance and cyclic stability were assessed. In one series of supercapacitors, mass of Ni(OH)2 was excessive while mass of AC was varied, the AC electrode thus constrained both the capacitance and the upper limit of cell voltage. Deficiency of AC resulted in lower specific capacitance and narrower cell voltage window but benefited to cyclic stability. In the other series of supercapacitors, the mass of AC was excessive whereas the mass of Ni(OH)2 was changeable in each cell, Ni(OH)2 electrode thus dominated both the capacitance and the lower limit of cell voltage. As a consequence, deficiency of Ni(OH)2 led to higher specific capacity and wider cell voltage window as well as lower cyclic stability. These results can contribute to improving understanding of and optimizing performance of asymmetric Ni(OH)2–AC capacitor. 相似文献
Carbon nano-onion (CNO) and Ni(OH)2 or NiO composites were prepared by chemical loading of Ni(OH)2 on the carbon surface. The samples were characterized by transmission electron microscopic (TEM) and scanning electron microscopic (SEM) methods, powder X-ray diffraction (XRD) technique and by differential-thermogravimetric analyses (TGA-DTG). The porosity properties were characterized by using nitrogen gas adsorption analyses. Pristine inorganic samples of NiO and Ni(OH)2 revealed different morphologies and porous characteristics when compared to those of the CNO composites, which showed unique electrochemical properties. The electrochemical performance of the CNO/Ni(OH)2 or CNO/NiO composites is largely affected by the mass, the morphology, the crystal phases of the inorganic component and the distribution of the Ni(OH)2/NiO phase. The CNO composites were used as materials for hybrid charge-storage devices. 相似文献
Multilayer super-short carbon nanotubes (SSCNTs) could be synthesized by tailoring the raw multiwalled carbon nanotubes with a simple ultrasonic oxidation-cut method. Nanostructured layered nickel hydroxide and SSCNTs have been successfully assembled to form Ni(OH)2/SSCNTs composite by electrostatic force. Compared with pure Ni(OH)2 (665 F g?1), the Ni(OH)2/SSCNTs composite exhibits the much better electrochemical performance with a specific capacitance of 1887 F g?1 at 1 A g?1, and demonstrates a good rate capability and excellent long-term cyclic stability (92 % capacity retention after 3000 cycles). It is the reason that the SSCNTs can form a conductive network onto the surface of Ni(OH)2 nanoflakes, and their excellent electric conductivity is advantaged to the charge transport on the electrode in discharge process and charge process. Therefore, the greatly enhanced capacitive performance of Ni(OH)2/SSCNTs can be attributed to a synergetic effect of Ni(OH)2 and SSCNTs. 相似文献
A novel composite of Ni(OH)2/ultra-stable Y zeolite materials was synthesized by an improved chemical precipitation method, which used the ultra-stable
Y zeolite as the template. The Ni(OH)2/ultra-stable Y zeolite composite and its microstructure were characterized by X-ray diffraction measurements and transmission
electron microscopy. Electrochemical studies were carried out using cyclic voltammetry, chronopotentiometry technology and
ac impedance spectroscopy, respectively. The result shows that the loose-packed whisker Ni(OH)2 phase has profound impacts on electrode performance at very high power output. A maximum discharge capacity of 185.6 mA-h/g
(1670 F/g), or 371 mA-h/g (3340 F/g) after correcting for weight percent of nickel hydroxide phase at the current density
of 625 mA/g could be achieved in a half-cell setup configuration for the Ni(OH)2/ultra-stable Y zeolite electrode, suggesting its potential application in electrode material for secondary batteries and
electrochemical capacitors. Furthermore, the effect of NH4Cl concentration on the electrochemical properties characteristics has also been systemically explored. 相似文献
Thermogravimetric analysis (TGA) has been used as a quick and accurate method for determining the content of Ni(OH)2 for nickel hydroxide electrodes (NOE) prepared by the chemical precipitation of nickel hydroxide on sintered nickel plaque. The analysis can be carried out in a reducing atmosphere (Ar+4%H2) or in air, and, while the final products differ, results for the two methods should be mutually consistant. The chemical reactions expected (in air vs. in hydrogen) are shown below:From the weight loss of this reaction the loading of Ni(OH)2 can be determined since the weight loss from the decomposition of pure Ni(OH)2 is 19.4%.Again the Ni(OH)2 loading can be calculated since the theoretical weight loss for the above reaction (i) is 36.7% (for pure Ni(OH)2).Portions of a commercial NOE were cut and used for the TGA experiments in air and in hydrogen atmospheres. These TGA experiments gave consistent results for the nickel hydroxide concentration of our NOE. X-ray diffraction (XRD) studies indicated the active material was crystalline nickel hydroxide. After TGA in air to 500°C, XRD showed only NiO (plus the Ni from the plaque), while after TGA in H2 to 500°C XRD showed only Ni peaks. In addition to these two chemical reactions, a weight loss of 1–3% was observed between 80–180°C corresponding to the loss of adsorbed H2O. The molar ratio of adsorbed water to the calculated Ni(OH)2 loading was about 0.1M H2O per mole of Ni(OH)2. This water was adsorbed and not structural based on the X-ray results discussed in this paper. 相似文献
Transition metal hydro/oxides (TMH/Os) are treated as the most promising alternative supercapacitor electrodes thanks to their high theoretical capacitance due to the various oxidation states and abundant cheap resources of TMH/Os. However, the poor conductivity and logy reaction kinetics of TMH/Os severely restrict their practical application. Herein, hierarchical core–shell P‐Ni(OH)2@Co(OH)2 micro/nanostructures are in situ grown on conductive Ni foam (P‐Ni(OH)2@Co(OH)2/NF) through a facile stepwise hydrothermal process. The unique heterostructure composed of P‐Ni(OH)2 rods and Co(OH)2 nanoflakes boost the charge transportation and provide abundant active sites when used as the intergrated cathode for supercapacitors. It delivers an ultrahigh areal specific capacitance of 4.4 C cm?2 at 1 mA cm?2 and the capacitance can maintain 91% after 10 000 cycles, showing an ultralong cycle life. Additionally, a hybrid supercapacitor composed with P‐Ni(OH)2@Co(OH)2/NF cathode and Fe2O3/CC anode shows a wider voltage window of 1.6 V, a remarkable energy density of 0.21 mWh cm?2 at the power density of 0.8 mW cm?2, and outstanding cycling stability with about 81% capacitance retention after 5000 cycles. This innovative study not only supplies a newfashioned electronic apparatus with high‐energy density and cycling stability but offers a fresh reference and enlightenment for synthesizing advanced integrated electrodes for high‐performance hybrid supercapacitors. 相似文献
Ni-PSZ composite coatings with various PSZ particle content were prepared by the electroforming technique. The microstructure and surface components of the coatings have been examined by optical microscopy, electron microscopy and X-ray photoelectron spectroscopy analysis and the wear properties of the coatings tested on a reciprocating wear test machine. The results show that the PSZ particles are uniformly dispersed in the coatings and thus increase the wear resistance of the coatings by inhibiting plastic deformation of the nickel matrix. The co-deposition of the PSZ particles in the electrolyte is mainly in the form of agglomeration and is accompanied by the incorporation of Ni(OH)2. When the PSZ content in a coating is higher than a critical value, the wear resistance of the coating could deteriorate because of the decrease in the integrity of the nickel matrix. After heat-treatment at high temperature, Ni(OH)2 in the coating is turned into Ni2O3 and NiO which can wet the PSZ particles and increase the bonding strength between the PSZ and nickel. In addition, the agglomerated PSZ particles are sintered when heat-treated. These are all beneficial to increasing the wear resistance of the coating. 相似文献
The development of efficient energy storage devices with high capacity and excellent stability is a demanding necessary to
satisfy future societal and environmental needs. A hybrid material composed of low defect density graphene-supported Ni(OH)2 sheets has been fabricated via a soft chemistry route and investigated as an advanced electrochemical pseudocapacitor material.
The low defect density graphene effectively prevents the restacking of Ni(OH)2 nanosheets as well as boosting the conductivity of the hybrid electrodes, giving a dramatic rise in capacity performance
of the overall system. Moreover, graphene simultaneously acts as both nucleation center and template for the in situ growth
of smooth and large scale Ni(OH)2 nanosheets. By virtue of the unique two-dimensional nanostructure of graphene, the as-obtained Ni(OH)2 sheets are closely protected by graphene, effectively suppressing their microstructural degradation during the charge and
discharge processes, enabling an enhancement in cycling capability. Electrochemical measurements demonstrated that the specific
capacitance of the as-obtained composite is high as 1162.7 F/g at a scan rate of 5 mV/s and 1087.9 F/g at a current density
of 1.5 A/g. In addition, there was no marked decrease in capacitance at a current density of 10·A/g after 2000 cycles, suggesting
excellent long-term cycling stability.
相似文献
The nanosized cathode material Ni(OH)2 powder for alkaline batteries was synthesized by solid-state reaction at room temperature through NiC2O4·2H2O as precursor, which was also prepared with solid-state reaction from nickel acetate and oxalic acid at ambient temperature. The precursor and the Ni(OH)2 samples were characterized by X-ray diffraction (XRD), infrared spectrometry (IR), transmission electron microscopy (TEM) and electrochemical testing. The results revealed that the as-synthesized Ni(OH)2 sample by this method is β(II)-type phase, and its shape is fibroid with the average particle size of 6–9 nm. Compared with microsized spherical β-Ni(OH)2, the nanosized β-Ni(OH)2 exhibits excellent electrochemical performance, such as lower polarization and better charge–discharge properties. 相似文献
Nano-sized Ni(OH)2 was synthesized by a co-precipitation method. Peaks between 500 and 750 cm−1 in Fourier transform infrared spectroscopy (FTIR) confirmed the presence of metal hydroxide stretching. Thermo gravimetric
analysis inferred that 69 wt% residue remained above 750 °C. High-resolution transmission electron microscopy analysis of
Ni(OH)2 revealed its size ranged from 80 to 110 nm with smooth morphology. Scanning electron microscopy inferred that pure Ni(OH)2 has nano rod-like morphology and higher weight percentage of aniline-intercalated Ni(OH)2 has agglomerated structure. UV–Vis spectrum detected the presence of Ni2+ ions at 210 nm and the existence of amino group in the basal spacing of Ni(OH)2 was not clearly appeared in the spectrum. Photoluminescence (PL) inferred that aniline-intercalated Ni(OH)2 showed higher PL intensity than the pristine poly(vinyl alcohol) its and nano composite. 相似文献
The self-propagating combustion behaviors of Nickel (Ni) and Aluminum (Al) thermites were studied as a function of bimodal Al particle size distributions. In particular, the low melting temperature of nano-scale Al particles coupled with the low concentrations of Al2O3 in micron-scale Al particles were exploited in order to optimize the macroscopic properties of the final alloy. Bimodal Al size distributions ranging from 0 to 50 wt% nano-Al combined with 50 wt% Ni were studied. Laser ignition experiments were performed on pressed pellets to determine flame propagation behavior and product microstructural features as a function of Al particle size. A new imaging technique is also presented that allows visualization of the surface reaction through highly luminescent flames and more accurate evaluation of burn rates. The wear behavior of the product alloy was measured and reported. Results show that composites composed of more micron-scale than nano-scale Al particles absorb more laser energy prior to flame propagation and experience an effective preheating. When 10–30 wt% nano Al is combined with micron Al and Ni, the wear resistance of the product alloy is optimized. Electron micrographs of the alloys suggest these properties may be attributed to whisker formations that behave as binding strings improving the overall abrasion resistance of the composite. 相似文献
In this work, nonmetallic S was doped into hierarchical Ni(OH)2 hollow microspheres by ethanol solvothermal method using thiourea as sulfur source. Although the morphology of precursor Ni(OH)2 is maintained, the surface states and pore properties had greatly changed after S doping. Using the as-prepared S-doped Ni(OH)2 as adsorbents for the removal of Congo red (CR), the S-doped Ni(OH)2 exhibited much better adsorption capacity compared with undoped Ni(OH)2. The adsorption behavior of both Ni(OH)2 and S-doped Ni(OH)2 followed the pseudo-second-order kinetic model and intraparticle diffusion model. The equilibrium data of Ni(OH)2 could be better fitted by Langmuir model, while Freundlich model could be better used to describe the S-doped Ni(OH)2 with a much larger adsorption capacity toward CR. The tuned microstructure and changed surface states of adsorbent after S doping may be responsible for the enhanced adsorption performance. Therefore, the doping of S species into hierarchical Ni(OH)2 paves a new way to tune the microstructure and surface states of Ni-based materials. 相似文献
Ni(OH)2 precursors were prepared via the precipitation transformation method, which was originated from Na2C2O4, NiSO4·6H2O and urea. NiO samples were successfully obtained by calcining Ni(OH)2 precursor with different calcination methods. Some were calcination in a tube furnace under the nitrogen flow and others were calcination in a muffle furnace. The products were well-characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of calcination methods on electrochemical performance of NiO samples were investigated. Moreover, the possible reason was proposed. The charge storage mechanism of NiO positive electrode in aqueous electrolyte was discussed. The electrochemical test showed that the as-prepared NiO prepared in a tube furnace can exhibit a good pseudocapacitance behaviour due to the higher utilization of active material. 相似文献
Graphene-based three-dimensional (3D) macroscopic materials have recently attracted increasing interest by virtue of their exciting potential in electrochemical energy conversion and storage. Here we report a facile one-step strategy to prepare mechanically strong and electrically conductive graphene/Ni(OH)2 composite hydrogels with an interconnected porous network. The composite hydrogels were directly used as 3D supercapacitor electrode materials without adding any other binder or conductive additives. An optimized composite hydrogel containing ～82 wt.% Ni(OH)2 exhibited a specific capacitance of ～1,247 F/g at a scan rate of 5 mV/s and ～785 F/g at 40 mV/s (～63% capacitance retention) with excellent cycling stability. The capacity of the 3D hydrogels greatly surpasses that of a physical mixture of graphene sheets and Ni(OH)2 nanoplates (～309 F/g at 40 mV/s). The same strategy was also applied to fabricate graphene-carbon nanotube/Ni(OH)2 ternary composite hydrogels with further improved specific capacitances (～1,352 F/g at 5 mV/s) and rate capability (～66% capacitance retention at 40 mV/s). Both composite hydrogels obtained here can deliver high energy densities (～43 and ～47 Wh/kg, respectively) and power densities (～8 and ～9 kW/kg, respectively), making them attractive electrode materials for supercapacitor applications. This study opens a new pathway to the design and fabrication of functional 3D graphene composite materials, and can significantly impact broad areas including energy storage and beyond. 相似文献
