The Formation of Layered Double Hydroxide Phases in the Coprecipitation Syntheses of [Ni0.80Co0.15](1−x)/0.95Alx(OH)2(anionn−)x/n (x = 0–0.2, n = 1, 2)

Abstract

This study investigates the synthesis of [Ni0.80Co0.15](1−x)/0.95Alx(OH)2 (x = 0–0.2) materials by coprecipitation to understand the formation of layered double hydroxide (LDH) phases as influenced by Al content and synthesis route. Two routes were compared: the first method dissolved all the metal reagents into one solution before addition into the reaction vessel, while the second dissolved Al into a separate NaOH solution before simultaneous addition of the Ni/Co and Al solutions into the reaction vessel. The synthesized materials were characterized by Scanning Electron Microscopy, X-ray Diffraction, Inductively Coupled Plasma-Optical Emissions Spectroscopy and Thermogravimetric Analysis to understand the formation of LDH phases as influenced by Al content and synthesis method. It was found that as Al content increased, the amount of LDH phase present increased as well. No significant difference in LDH phase presence was observed for the two synthesis methods, but the morphologies of the particles were different. The method containing all the metals in one solution produced small particles, likely due to the continuous nucleation of Al(OH)3 disrupting particle growth. The method containing the separate Al in NaOH solution matched the morphology of the material with no Al, which is known to form desired large spherical particles under continuously stirring tank reactor synthesis conditions.