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Nickel(II) hydroxide is the inorganic compound with the formula Ni(OH)2. It is an apple-green solid that dissolves with decomposition in ammonia and amines and is attacked by acids. It is electroactive, being converted to the Ni(III) oxy-hydroxide, leading to widespread applications in rechargeable batteries.
Nickel(II) hydroxide is the inorganic compound with the formula Ni(OH)2. It is an apple-green solid that dissolves with decomposition in ammonia and amines and is attacked by acids. It is electroactive, being converted to the Ni(III) oxy-hydroxide, leading to widespread applications in rechargeable batteries.
Properties
Nickel(II) hydroxide has two well-characterized polymorphs, α and β. The α structure consists of Ni(OH)2 layers with intercalated anions or water. The β form adopts a hexagonal close-packed structure of Ni2+ and OH− ions. In the presence of water, the α polymorph typically recrystallizes to the β form. In addition to the α and β polymorphs, several γ nickel hydroxides have been described, distinguished by crystal structures with much larger inter-sheet distances. The mineral form of Ni(OH)2, theophrastite, was first identified in the Vermion region of northern Greece, in 1980. It is found naturally as a translucent emerald-green crystal formed in thin sheets near the boundaries of idocrase or chlorite crystals. A nickel-magnesium variant of the mineral, had been previously discovered at Hagdale on the island ofUnst
Unst (; sco, Unst; nrn, Ønst) is one of the North Isles of the Shetland Islands, Scotland. It is the northernmost of the inhabited British Isles and is the third-largest island in Shetland after Mainland and Yell. It has an area of .
Unst ...
in Scotland.
Reactions
Nickel(II) hydroxide is frequently used in electrical car batteries. Specifically, Ni(OH)2 readily oxidizes to nickel oxyhydroxide, NiOOH, in combination with a reduction reaction, often of a metal hydride (reaction 1 and 2). Reaction 1 Reaction 2 Net Reaction (in H2O) Of the two polymorphs, α-Ni(OH)2 has a higher theoretical capacity and thus is generally considered to be preferable in electrochemical applications. However, it transforms to β-Ni(OH)2 in alkaline solutions, leading to many investigations into the possibility of stabilized α-Ni(OH)2 electrodes for industrial applications.Synthesis
The synthesis entails treating aqueous solutions of nickel(II) salts with potassium hydroxide.Glemser, O. (1963) "Nickel(II) Hydroxide" in ""Handbook of Preparative Inorganic Chemistry'', 2nd ed. G. Brauer (ed.), Academic Press, NY. Vol. 1. p. 1549.Toxicity
The Ni2+ ion is a known carcinogen. Toxicity and related safety concerns have driven research into increasing the energy density of Ni(OH)2 electrodes, such as the addition of calcium or cobalt hydroxides.See also
*List of minerals named after people
This is a list of minerals named after people. The chemical composition follows name.
A
* Abelsonite: C31H32N4Ni – American physicist Philip Hauge Abelson (1913–2004)alfred
*Abswurmbachite: Cu2+Mn3+6O8SiO4 – German mineralogist I ...
* Nickel-cadmium battery
* Nickel hydrogen battery
*Nickel metal hydride battery
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
* Nickel-iron battery
References
{{Hydroxides Nickel compounds Hydroxides