Obtention of a cobalt-bearing coating using spent batteries as raw materials

The extensive use of smartphones is increasingly generating technological waste, such as the spent lithium-ion spent batteries, which contains potentially toxic metals that may affect the environment. These metals can be recovered and used as raw material for new industrial applications, such as the production of metal coatings. In this work, a sample of spent lithiumion batteries was manually disassembled, to extract transition metal-rich cathodes. The cathodes were separated and crushed in a blade mill, to obtain a cobalt-rich concentrate powder by sieving. The powder was leached using a 1.11 M citric acid solution amended with hydrogen peroxide (1.25% volume), at 74°C under stirring at 300 rpm. The obtained polymetallic liquor was analyzed for Co, Li, Mn, and Ni, then it was submitted for electrolysis to produce metal coatings over pure copper substrates. This electrochemical electrodeposition was studied by means of cyclic voltammetry and chronoamperometry, using electrolytic Cu as a working electrode (substrate), a reference electrode Ag/AgCl and an auxiliary graphite electrode. The visual appearance of the obtained coatings was analyzed by an Olympus SZ61 stereoscope, with images at a magnification of 120x. The results showed that by applying a -950 mV vs Ag/AgCl electrodeposition potential, a homogeneous coating with good adhesion and better visual appearance was obtained. In addition, at this potential, there was little influence of the reaction of hydrogen evolution reaction during the production of the coatings.