Electrochemical Study of Zinc-Substituted Nickel Hydroxide

Abstract

The electrochemical behavior of ␣and ␤͑II͒-type zinc-substituted nickel hydroxides is studied during a galvanostatic cycling in a KOH electrolyte. It is shown that these materials exhibit very stable capacities during long-term cycling. When using an 8 M KOH electrolyte, the ␤͑III͒/␤͑II͒ system is stabilized, after the initial formation of ␥-type phases during the first charges. The higher the amount of zinc in the starting material, the faster this stabilization occurs. The substitution of zinc for nickel is also shown to delay the formation of the ␥-phase upon charge, when various KOH electrolytes, with increasing concentrations, are successively used. A model is proposed to explain these results; it is based on several processes, occurring simultaneously either via the solution or through solid-state reactions, with a partial loss of zinc.

Comparative structural and electrochemical study of high density spherical and non-spherical Ni(OH)2 as cathode materials for Ni–metal hydride batteries

“…But till now, non-spherical Ni(OH) 2 has attracted little attention as raw material for the positive electrode in commercial batteries because non-spherical powders always show a lower tapdensity (1.5-1.8 g cm −3 ) [8,23]. Most studies about non-spherical Ni(OH) 2 in the literature mainly focused on either the properties of Ni(OH) 2 electrodes for rechargeable Cd-Ni and Ni-MH batteries or the crystal chemistry of Ni(OH) 2 [24][25][26][27]. In the previous work [22], we have studied the effect of tap-density on the electrochemical performance of non-spherical Ni(OH) 2 electrodes.…”

Effect of crystallinity on the electrochemical performance of nanometer Al-stabilized α-nickel hydroxide

“…Partial substitution of nickel ion in the nickel hydroxide lattice by other metal ions, such as Al [9,11], Co [11,12], Fe [13], Mn [14] and Zn [15,16], is the commonly used method to prepare a stable ␣-Ni(OH) 2 , among which Al is the most attractive because Al-substituted ␣-Ni(OH) 2 has relatively better electrochemical performance. Chemical co-precipitation, electrochemical impregnation and the 'chimie douce' techniques are the three common used methods to prepare ␣-Ni(OH) 2 [17], while homogeneous precipitation in the presence of urea, usually called urea decomposition, can also produce Ni(OH) 2 .…”

Influence of ammonia concentration on anodic deposition of nickel oxide

“…On the negative sweep the cathodic current peak at about Ni(II) -ClNi 2+ + Clfi NiCl + 0 0.75 V is obviously divided into two current peaks C11 and C12. As has been reported in the literature [20][21][22], nickel hydroxide may exist in at least two different crystallographic forms a-Ni(OH) 2 and b-Ni(OH) 2 , hydrous and anhydrous, respectively. In addition, the oxidization of nickel hydroxide gives two other varieties of oxyhydroxides, b-NiOOH and c-NiOOH.…”