Nickel hydroxides and related materials: a review of their structures, synthesis and properties

Abstract

This review article summarizes the last few decades of research on nickel hydroxide, an important material in physics and chemistry, that has many applications in engineering including, significantly, batteries. First, the structures of the two known polymorphs, denoted as α-Ni(OH) 2 and β-Ni(OH) 2 , are described. The various types of disorder, which are frequently present in nickel hydroxide materials, are discussed including hydration, stacking fault disorder, mechanical stresses and the incorporation of ionic impurities. Several related materials are discussed, including intercalated α-derivatives and basic nickel salts. Next, a number of methods to prepare, or synthesize, nickel hydroxides are summarized, including chemical precipitation, electrochemical precipitation, sol-gel synthesis, chemical ageing, hydrothermal and solvothermal synthesis, electrochemical oxidation, microwaveassisted synthesis, and sonochemical methods. Finally, the known physical properties of the nickel hydroxides are reviewed, including their magnetic, vibrational, optical, electrical and mechanical properties. The last section in this paper is intended to serve as a summary of both the potentially useful properties of these materials and the methods for the identification and characterization of 'unknown' nickel hydroxide-based samples.

Nickel speciation in cement-stabilized/solidified metal treatment filtercakes

“…The peak at 640°C suggests about 8.8% calcium carbonate [31], that at 432°C is likely about 19% uncarbonated calcium hydroxide, and that at around 96°C may be attributable to moisture, molecular water, or hydroxyl groups. In general, mass loss of both filtercakes is gradual, suggesting multiple overlapping thermal decomposition processes, and/or incongruent decomposition of amorphous, impure and/or metastable phases, which could include nickel hydroxide [32].…”

“…-nickel hydroxide is a compound of considerable interest due to its applications in alkaline storage batteries (e.g., Ni-Cd, Ni-Zn, Ni-Fe, and Ni-MH) and catalysts. Its characteristics, including the layered double hydroxide (LDH) structure of both -and -nickel hydroxides is reviewed by Hall et al [32], whereby Ni can be substituted by other multivalent cations, Al, Zn, Co, etc.. -nickel hydroxide is metastable and is supposed to convert to the more stable  form over time. Dissolved ions such as Al and Zn in highly alkaline chemical environments can, however, prevent that phase transformation [36].…”

Study of the influence of the template concentration under homogeneous precepitation on the properties of Ni(OH)2 for supercapacitors

“…This leads to the formation of materials similar to polymer composites [29]. The paper [30] has demonstrated the use of water-soluble templates for the synthesis of nickel hydroxide.…”

Electrodeposition of Nickel Hydroxide Nanoparticles on Carbon Nanotube Electrodes: Correlation of Particle Crystallography with Electrocatalytic Properties

“…shows that the β phase (inter-sheet (001) distance, cₒ = 4.60 Å) adopts a more close packed (dehydrated) structure compared to the more disordered (cₒ = 7.60 Å) hydrated  phase ( Figure 6a). [65][66][67] For the direct approach, it is likely that the rapid precipitation process in the presence of Ni 2+ and supersaturated concentrations of OH -(generated electrochemically) is responsible for α-phase formation, favoring the formation of disordered α-Ni(OH) 2 (kinetically-driven process).…”