Structural, textural and electrochemical characterization of a novel nickel hydroxide nanoparticles obtained at high current density electrolysis Technique

F.J. RODRÍGUEZ NIETO; D. BECKER; L. ANDRINI; S.J.A. FIGUEROA

Xiamen

Congreso; 3rd International Colloids Conference ? Colloids and Energy; 2013

It?s widely known that the Nickel Hydroxide is an importantly and functional material with multiple applications, principally in battery technology [1]. Nickel hydroxide has a hexagonal layered structure with two polymorphs forms, namely a and b [2]. The a-form is isostructural with hydrotalcite (HT)-like compounds and consists on a stacking of positively charged Ni(OH)2-x layers, with intercalated anions and water molecules in the interlayer space in order to restore the charge neutrality; if the slabs are oriented randomly with respect to one another, leading to turbostratic disorder. The beta-form possesses a brucite like Mg(OH)2 structure and does not contain any intercalated species. In this structure, the OH ions are hexagonally packed and the nickel ions occupy alternate rows of octahedral sites leading to layered structure which can described as an ordered stacking of charge neutral layers of Ni(OH)2. However, the a-nickel hydroxide is a metastable phase and is difficult to synthesize because it changes rapidly to the b-form during synthesis or on storage in a strong alkali[3]. Actually it is recognized that the overallperformance of nickel cathodes depends on the microstructure, textural characteristics, and the crystallite size of the active material [4].There are many researches showing compositional disorders, partial substitution of cobalt, iron, manganese, aluminum and zinc were made to stabilize the alpha-Ni(OH)2 phase. In general, the type, quantity and way to incorporate the modifiers can change the electrochemical performance of the nickel hydroxide electrode. In this work we explore la possibility of obtain a y/o b nickel hydroxide at level semi micro using an electrochemical method.Ni(OH)2 is a complex crystalline material, in which the sample preparation is key to change the structure and redox properties. We optimize the experimental conditions to produce alpha and beta-phases modified with Co doping. There is no evidence of Co sustitution on Ni(OH)2 structure. Co is mostly on the surface of the material, probably as a mixture: Co(OH)2 and CoO. The Ni is arranged in NiO6 disterted octahedra, as expected for the Ni(OH)2 structure. There is a decreasing in the Ni-O coordination number with the Co incorporation and an increase in the Ni-O distance with Co incorporation on NiCo-TCC. The obtained powders shown different disorder degrees, showing a quasi-amorphic structure with different stacking fault forms.[1] A.K. Shuklaa et al., J. Power Sources 100, 125 (2001). D. Linden, T.B. Reddy, Handbook of Batteries, Third Edit, McGraw-Hill, 2002.[2] P. Oliva et al., J. Power Sources. 8, 229 (1982).[3] F.Portemer et al., J. Electrochem. Soc. 139, 671 (1992).[4] M. Figlarz et al., Solid State Ionics 43, 143 (1990). J. Chen et al., Electrochem. Soc. 146, 3606 (1999). T. N. Ramesh et al., J. Electrochem. Soc. 152, 4, A806 (2005).