Performance Of Nickel Hydroxide Electrode Research Articles

Effect of cobalt electroless deposition on nickel hydroxide electrodes

The effects of cobalt additive on the positive electrode surface of nickel alkaline batteries are investigated. Electrode surface modifications by electroless cobalt deposits were made at different immersion times. The performance of nickel hydroxide electrodes was studied by optical techniques, such as scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and electrochemical methods as cyclic voltammetry, charge–discharge curves and electrochemical impedance spectroscopy (EIS). According to these results, electroless cobalt deposits obtained with 5 min of immersion time in the electroless-bath exhibit a better electrode performance.

Effects of different electrolytes containing Na2WO4 on the electrochemical performance of nickel hydroxide electrodes for nickel–metal hydride batteries

To improve the high-temperature performance of the nickel hydroxide electrodes in nickel–metal hydride batteries, sodium tungstate (Na2WO4) used as an electrolyte additive has been added into two types of binary electrolytes (KOH–LiOH and NaOH–LiOH) in this study. The effects of electrolyte composition on the electrochemical performance of nickel electrodes have been systematically investigated via a combination of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and charge/discharge tests. It is found that by adding (1.0 wt.%) Na2WO4, the performance of nickel electrodes is significantly improved in both NaOH and KOH electrolytes at 70 °C. The improved performance can be attributed to the deposition of WO3·2H2O solid film on the surface of nickel electrode, which is beneficial to the increase in oxygen evolution overpotential, the slow-down of oxygen evolution rate and the decrease in charge-transfer resistance.

Effect of Doped Metal Ions on the Electrochemical Performance of Nickel Hydroxide Electrode for Nickel/Metal Hydride Battery

Positive materials for nickel/metal hydride battery, nickel hydroxide doped by different metal ions were synthesized by coprecipitation, and subsequent hydrothermal treatment and anion exchange method. The structure of the samples was analyzed by XRD test, and the electrochemical performances were studied by galvanostatic charge-discharge, cyclic voltammetry and impedance tests. The obtained electrode material shows mainly β-Ni (OH)2structure when only doping Zn2+, while α-Ni (OH)2structure was obtained by only doping Al3+or co-doping Al3+and Zn2+. Ni (OH)2co-doped Al3+and Zn2+had fine cyclic stability, high number of exchanged electrons per nickel atom (the maximum is 1.93), small charge-transfer and proton-diffusion resistances.

Enhanced electrochemical performance of nickel hydroxide electrode with monolayer hollow spheres composed of nanoflakes

Nickel hydroxide electrodes with hollow spheres were fabricated using a PS (polystyrene) sphere template and electrochemical deposition. The nickel hydroxide grew perpendicular to the electrode substrate during anodic deposition and around the PS spheres during cathodic deposition. After the removal of the PS template, hollow spheres or open hollow spheres were formed via cathodic deposition. The nickel hydroxide electrode with hollow spheres and nanoflakes showed greatly enhanced electrochemical performance in alkaline solution compared with the bare nickel hydroxide electrode. The opening of the hollow spheres facilitated easy electrolyte transport to the reaction sites and led to a further increase in the specific capacitance of the nickel hydroxide electrode. The specific capacitance of the electrode with the open hollow spheres reached 800 F g −1, which was much higher than that of the bare electrode (224 F g −1) and the hollow-sphere electrode (342 F g −1) at a discharge current density of 10 A g −1.

Effects of addition of different carbon materials on the electrochemical performance of nickel hydroxide electrode

Nickel hydroxide is used as an active material in positive electrodes of rechargeable alkaline batteries. The capacity of nickel–metal hydride (Ni–MH) batteries depends on the specific capacity of the positive electrode and utilization of the active material because of the Ni(OH) 2/NiOOH electrode capacity limitation. The practical capacity of the positive nickel electrode depends on the efficiency of the conductive network connecting the Ni(OH) 2 particle with the current collector. As β-Ni(OH) 2 is a kind of semiconductor, the additives are necessary to improve the conductivity between the active material and the current collector. In this study the effect of adding different carbon materials (flake graphite, multi-walled carbon nanotubes (MWNT)) on the electrochemical performance of pasted nickel–foam electrode was established. A method of production of MWNT special type of catalysts had an influence on the performance of the nickel electrodes. The electrochemical tests showed that the electrode with added MWNT (110–170 nm diameter) exhibited better electrochemical properties in the chargeability, specific discharge capacity, active material utilization, discharge voltage and cycling stability. The nickel electrodes with MWNT addition (110–170 nm diameter) have exhibited a specific capacity close to 280 mAh g −1 of Ni(OH) 2, and the degree of active material utilization was ∼96%.

Effect of nickel hydroxide composition on the electrochemical performance of spherical Ni(OH) 2 positive materials for Ni–MH batteries

A special method “conduit synthesis technology” has been utilized to produce spherical nickel hydroxide powders with different chemical compositions. Three kinds of powers A, B, C were prepared by chemically coprecipitating Ni, Co, Zn, Ca, Mg and Cu. It was found that powder B produced better performance than the others. The discharge capacities of powder B could achieve 280 mAh g −1 for both 1C and 2C rates at 65 °C, respectively. The cyclic voltammetry analysis showed that the difference between the oxidation potential and the oxygen evolution potential of powder B is 122 mV. It indicated that Co could improve conductivity of electrons, restrict the oxygen evolution reaction and thus promote the high rate charge/discharge and high-temperature performance. Ca and Mg might effectively enhance the oxygen evolution potential in the charge process. Furthermore, the proper addition of Zn, Ca and Cu could lower the ionization energy and elevated the transition energy, and thus the transfer of electrons in electrode materials was accelerated and the electrochemical performance of nickel hydroxide electrode was improved. It was a promising way to improve the electrochemical performance of spherical nickel hydroxide for Ni–MH batteries.

The effect of stacking faults on the electrochemical performance of nickel hydroxide electrodes

The crystal structure of nickel hydroxide comprises of a repetitive stacking of charge neutral layers AbC AbC AbC. A and C denotes the hydroxyl ions which are hexagonally close packed, while b denotes the divalent nickel ions occupying octahedral interstitial sites. The random incorporation of other layers, such as AcB, BaC, CbA, etc., within AbC AbC AbC … stacking sequence can lead to the formation of stacking faults. DIFFaX simulations show that each kind of stacking fault produces a characteristic pattern of non-uniform broadening of the peaks corresponding to the ( h 0 ℓ) reflections in the powder X-ray diffraction (PXRD) pattern of nickel hydroxide. The electrochemical property of each two types of stacking faulted nickel hydroxide is investigated. 2H 2 type of stacking faulted nickel hydroxide delivers better electrochemical activity compared to 3R 2 type stacking faulted nickel hydroxide.

Study on the Electronic Structure of Doped Nickel Hydroxide Using the DV-Xα Method of Quantum Chemistry

The electronic structures of Ni 7O 12H 2+ 12, Ni 6ZnO 12H 2+ 12, Ni 6CuO 12H 2+ 12, and Ni 6CaO 12H 2+ 12 clusters were calculated using the DV-X? method of quantum chemistry. By analyzing the density of states, the orbital populations, the net charges, the ionization energies, the transition energies, and the electric charge density differences of the selected clusters, it was indicated that the interaction between Ni and O was enhanced by adding Zn and Cu to nickel hydroxide, and the Ni?O bond was extended. As a result, the structural stability of nickel hydroxide was improved and the cycling life of the electrode was extended. However, the addition of Ca weakened the interaction. The ionization energy was dropped and the transition energy was elevated by the doping of Zn, Cu, and Ca, and thus the transfer of electrons in electrode materials was accelerated and the electrochemical performance of nickel hydroxide electrode was improved. However, excessive Ca-doped will change the structure of nickel hydroxide and will deteriorate its electrochemical performance.

05/02090 Influence of nanosized Ni(OH) 2 addition on the electrochemical performance of nickel hydroxide electrode

05/02090 Influence of nanosized Ni(OH) 2 addition on the electrochemical performance of nickel hydroxide electrode

Synthesis, Characterization, and Electrochemical Application of Ca(OH)2-, Co(OH)2-, and Y(OH)3-Coated Ni(OH)2 Tubes

We report on the synthesis, characterization, and electrochemical application of Ca(OH)2-, Co(OH)2-, and Y(OH)3-coated Ni(OH)2 tubes with mesoscale dimensions. These composite tubes were prepared via a two-step chemical precipitation within an anodic alumina membrane under ambient conditions. The morphology and structure of the as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) equipped with energy dispersive spectroscopy (EDS). The results showed that the size of the tubes was of mesoscale dimension and the proportion of the tube morphology was about 95%. The as-prepared composite tubes were further investigated as the positive-electrode materials of rechargeable alkaline batteries. Electrochemical measurements revealed that the Ni(OH)2 tubes coated with Ca(OH)2, Co(OH)2, and Y(OH)3 exhibited superior electrode properties including high discharge capacity, excellent high-temperature and high-rate discharge ability, and good cycling reversibility. The mechanism analysis suggests that both the coated layers and the unique hollow-tube structures play an indispensable role in optimizing the electrochemical performance of nickel hydroxide electrodes.

Influence of nanosized Ni(OH)2 addition on the electrochemical performance of nickel hydroxide electrode

Nanosized cathode material Ni(OH)2 for alkaline batteries was prepared by converting the precursor of NiC2O4·2H2O in KOH water solution which contained Tween-80, and the precursor was obtained via the reaction between Ni(NO3)2·6H2O and H2C2O4·2H2O in ethanol solvent. The products were characterized using X-ray diffraction (XRD), infrared absorption spectroscopy (IR), and transmission electron microscopy (TEM). The results showed that the as-prepared Ni(OH)2 sample by this method is β(II)-type phase and its shape is spherical with the particle size from 5 to 35 nm. The electrochemical studies revealed that the 10% addition of nanosized Ni(OH)2 to common microsized spherical Ni(OH)2 can improve the electrochemical performance of the Ni(OH)2 electrode. There exists approximately a 10% improvement in the utilization of the active material of the Ni(OH)2 electrode with 10% nannosized Ni(OH)2 addition in comparison with microsized spherical Ni(OH)2 electrode. Nanosized Ni(OH)2 may be a promising cathodic active material for alkaline rechargeable batteries.

Effect of Different Species of Cobalt Additive on Performance of Nickel Hydroxide Electrode

Effect of Different Species of Cobalt Additive on Performance of Nickel Hydroxide Electrode

Electrochemical impregnation and performance of nickel hydroxide electrodes with porous plaques of hollow nickel fibres

Porous plaques that contain hollow nickel fibres are successfully prepared by a traditional slurry-scraping technology. The fibrous, nickel-plaque materials have high porosity (85–87%) and are for application in high specific-energy nickel—metal hydride batteries. Nickel electrodes are fabricated by cathodic electrodeposition from metal nitrate solutions on to the fibrous plaques. Parameter changes in the concentration of nickel nitrate, current density, pH, temperature and plaque porosity, as well as changes in the impregnation time, are examined with respect to their influence on the weight gain of fibrous nickel plaques. The influence of fibre content on the electrode performance is investigated by determining the capacity, utilization, expansion and cycling characteristics. Both C-type and D-type electrodes with ∼ 85% fibrous plaques reach a specific capacity of 141 mAh g −1. It is found that utilization of active material and electrode swelling both decrease with increasing content of the hollow fibres.

Electrochemical impregnation and performance of nickel hydroxide electrodes with porous plaques of hollow nickel fibres

Electrochemical impregnation and performance of nickel hydroxide electrodes with porous plaques of hollow nickel fibres