Study of High Purity Cobalt Carbonate Nanocrystals Production by Microemulsion as Batteries Precursors

Abstract

The precipitation of cobalt carbonate nanocrystals was achieved through the reaction of a pure and rich solution of cobalt sulphate (Co2+: 16.80 g/l) with a solution of carbonate solution (200 g/l). A surfactant was added to the reacting mixture in order to control the shape and size of generated crystallites. Two parameters were then varied i.e., the weight of surfactant agent and the precipitation time in accordance with Taguchi’s L4 full experimental procedure (22). Chemical and structural characterizations tests of the obtained precipitates were done through X-Rays Fluorescence (XRF), Scanning Electron Microscopy (SEM) and X-Rays Diffractometer (XRD); whereas the size of crystallites was assessed according to the Laue-Scherrer formula. The results obtained from the variance analysis (ANOVA) indicated an optimal size of cobalt carbonate’s crystallites of 13 nm with a cobalt content of 44.35% (equivalent to 89.45% of CoCO3) at ambient temperature under the following conditions: pH = 7; Mixing speed: 800 tr/min; Surfactant weight: 8 g; and a mixing time: 10 minutes. SEM images revealed an agglomeration of the obtained nanocrystals due to suspected drying conditions i.e., drying temperature and drying atmosphere. It is suggested that the experiment should be conducted under neutral conditions at a temperature below that of cobalt carbonate’s decomposition (181.41℃).