SYNTHESIS OF NICKEL HYDROXIDE IN THE PRESENCE OF ACETATE ION AS A «SOFT» LIGAND FOR APPLICATION IN CHEMICAL POWER SOURCES

Nickel hydroxide is widely used as the active material in chemical power sources. The formation mechanism of nickel hydroxide includes two fast phases of the formation of an initial amorphous particle and slow aging (crystallization) stage. Characteristics of nickel hydroxide can be improved by slowing down the first stage through the reaction of nickel cation with «soft» ligand and formation of a weak complex. It is proposed to use acetate ion as a «soft» ligand, which forms a complex with Ni2+ without the outer sphere. The influence of acetate ion on the crystal structure, particle morphology and electrochemical properties of nickel hydroxide chemically precipitated at high supersaturation using nickel sulfate in the presence and absence of sodium acetate is studied. The crystal structure of the samples is studied by means of X-ray diffraction analysis and sample morphology – by means of scanning electron microscopy, electrochemical properties – cyclic voltammetry. A comparative analysis of the characteristics of the samples prepared in the presence and absence of sodium acetate is carried out. The results of XRD analysis revealed that synthesis in the presence of acetate ion leads to the formation of a bi-phase system that contains low crystallinity β-Ni(OH)2 and α-Ni(OH)2. This also leads to a higher content of smaller particles with a larger surface area. The comparative analysis of electrochemical characteristics revealed the formation of a more active samples in the presence of acetate ions, which predominantly behaves like the α-form. The sample activity increased during cycling. Synthesis in the presence of acetate ion results in the increase of specific discharge peak current (equivalent to electrochemical activity) by 1.93 times, in comparison to the sample synthesized under the same condition but in the absence of acetate ion