Nickelous hydroxide oxide

When nickel hydroxide is oxidized at the nickel electrode in alkaline storage batteries the black trivalent gelatinous nickel hydroxide oxide [12026-04-9], Ni(0H)0, is formed. In nickel battery technology, nickel hydroxide oxide is known as the nickel active mass (see Batteries, secondary cells). Nickel hydroxide nitrate [56171-41-6], Ni(0H)N02, and nickel chloride hydroxide [25965-88-2], NiCl(OH), are frequently mentioned as intermediates for the production of nickel powder in aqueous solution. The binding energies for these compounds have been studied (55). 

This is the mechanism of an indirect electrolysis, where the nickel oxide hydroxide acts as an electrocatalyst that is continuously renewed. Some observations, however, are not consistent with this mechanism. The addition of an oxidizable alcohol should lead to an increase of the current for the nickel hydroxide oxidation and a decrease for its reduction This is not the case. The currents for nickel hydroxide and nickel oxide hydroxide remain unchanged, whilst at more anodic potential a new peak for the alcohol oxidation appears. This problem has also been addressed by Vertes... 

The lower amines have been oxidized in similar yields to nitriles at silver oxide and copper oxide anodes Activation of the electrode by deposition of a nickel hydroxide oxide layer is less essential than with alcohols due to the higher reactivity... 

Die selektive Oxidation von Hydroxy-Gruppen in Steroiden kann erfolgreich mit elektro-chemisch erzeugtem Nickel-hydroxid-oxid durchgefiihrt werden82. 

Nickel Salts and Chelates. Nickel salts of simple organic acids can be prepared by reaction of the organic acid and nickel carbonate of nickel hydroxide reaction of the acid and a water solution of a simple nickel salt and, in some cases, reaction of the acid and fine nickel powder or black nickel oxide. 

There are many methods of fabricating the electrodes for these cell systems. The eadiest commercially successhil developments used nickel hydroxide [12054-48-7] Ni(OH)2, positive electrodes. These electrodes are commonly called nickel electrodes, disregarding the actual chemical composition. Alkaline cells using the copper oxide—2inc couple preceeded nickel batteries but the CuO system never functioned well as a secondary battery. It was, however, commercially available for many years as a primary battery (see BatterieS-PRIMARY cells). 

Electrodes. A number of different types of nickel oxide electrodes have been used. The term nickel oxide is common usage for the active materials that are actually hydrated hydroxides at nickel oxidation state 2+, in the discharged condition, and nickel oxide hydroxide [12026-04-9] NiO OH, nickel oxidation state 3+, in the charged condition. Nickelous hydroxide [12034-48-7J, Ni(OH)2, can be precipitated from acidic solutions of bivalent nickel... 

Almost all the methods described for the nickel electrode have been used to fabricate cadmium electrodes. However, because cadmium, cadmium oxide [1306-19-0], CdO, and cadmium hydroxide [21041-95-2], Cd(OH)2, are more electrically conductive than the nickel hydroxides, it is possible to make simple pressed cadmium electrodes using less substrate (see Cadmium and cadmium alloys Cadmium compounds). These are commonly used in button cells. 

The nickel oxide modification obtained electrochemicaHy in KOH electrolyte contained potassium ion and its nickel oxidation level are higher than that of NiO 5. Conclusions regarding the transitions between the reduced and oxidized products within the two series are that the redox process was not reversible and although the oxidized phases of the P- and the y-nickel hydroxides differ in energy contents, differences in analyses and x-ray patterns are not significant. 

Jfickeloxydul, n. nickelous oxide, nickel(II) oxide, NiO. -hydrat, n, nickelous hydroxide, nickel (II) hydroxide, -salz, n. nickelous salt, nickel(II) salt, -verbindung,/. nickelous compound, nickel(II) compound. Nickelpapier, n. nickel foil, nickelplattiert, a. nickel-plated. 

Lithium-nickel oxides form various lithium compounds, lithium hydroxides (LiOH), Li2C03, nickel hydroxide (Ni(OH)2), nickel carbonate (NiC03) and nickel oxide (NiO). Figure 51 shows the discharge characteristics of lithium-nickel oxides synthesized from these compounds. They were heat-treated at 850 °C for 20 h in air. Although the lithium nickel oxides showed a smaller discharge capacity than that of LiCo02, LiOH and Ni(OH)2 were considered to be appropi-ate raw materials. 

In normal battery operation several electrochemical reactions occur on the nickel hydroxide electrode. These are the redox reactions of the active material, oxygen evolution, and in the case of nickel-hydrogen and nickel-metal hydride batteries, hydrogen oxidation. In addition there are parasitic reactions such as the corrosion of nickel current collector materials and the oxidation of organic materials from separators. The initial reaction in the corrosion process is the conversion of Ni to Ni(OH)2. 

In acidic electrolytes only lead, because it forms passive layers on the active surfaces, has proven sufficiently chemically stable to produce durable storage batteries. In contrast, in alkaline medium there are several substances basically suitable as electrode materials nickel hydroxide, silver oxide, and manganese dioxide as positive active materials may be combined with zinc, cadmium, iron, or metal hydrides. In each case potassium hydroxide is the electrolyte, at a concentration — depending on battery systems and application — in the range of 1.15 - 1,45 gem"3. Several elec-... 

For alkaline storage batteries requirements are often demanded exceeding by far those for lead storage batteries. The reason is that the suitable materials for the positive electrode are very expensive (silver oxide, nickel hydroxide) and thus the use of these storage batteries is only justified where requirements as to weight, number of cycles, or temperature range prohibit other solutions. Besides a few standardized versions — mainly for nickel-cadmium batteries — this has led to the existence of a large diversity of constructions for special applications [4-6, 108, 109],... 

The oxidation of hydrazine follows the change in surface completely since it oxidizes rapidly on bare nickel and again on the nickel(III) oxide surface but in the intermediate potential region, where the surface is covered with nickel(II) hydroxide, the anodic oxidation cannot occur (Fleischmann etal., 1972d). 

Oxidation of Organic Compounds at the Nickel Hydroxide Electrode H.-J. Schafer... 

The mixed chromium and nickel (5% and 10% Ni atomic) catalysts were prepared by dehydration of mixed chromium and nickel hydroxides prepared by adding an ammonia solution to a solution of chromium and nickel nitrate in order to maintain a pH = 7 1. The final pH was equal to 7.S. The hydroxyde treatment was the same as the one already described for chromium oxide. 

Sandorfy, C. Vibrational Spectra of Hydrogen Bonded Systems in the Gas Phase. 120, 41-84 (1984). Schafer, H.-J. Oxidation of Organic Compounds at the Nickel Hydroxide Electrode. 142, 101-129 (1987). 

Mixing of the electrode products causes hydrolytic precipitation of the nickel and, after separation of the nickel hydroxide, the filtrate was returned to the cells. The sequence of the electrolytic purification steps is outlined in Figure 6.28. Nickel hydroxide slurry is first added to the anolyte for the purpose of raising the pH to 3.7 (2 H+ + Ni(OH) = Ni2+ + 2 H20), and iron(II) is oxidized by introducing chlorine. This causes hydrolytic precipitation of the iron(III) and corrects the nickel ion deficiency by the low anodic current efficiency. The iron(III) hydroxide is removed by filteration. The clarified solution is then treated with nickel carbonate and further chlorine to oxidize the cobalt(II) and allow its separation as cobalt(I II) hydroxide. 

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