Optimization of metals extraction from spent lithium-ion batteries by sulphuric acid and sodium metabisulphite through a techno-economic evaluation

Abstract

The main factors that affect the extraction of metals from spent lithium-ion batteries by acid leaching using H₂SO₄, and sodium metabisulphite, were evaluated and optimized through a set of experiments, framed by a techno-economic approach. The maximum value of the profit response was obtained with the highest possible values of acid concentration (2.5 M) and time (2 h), a liquid/solid ratio of 5 L/kg, and the lowest possible value of temperature (40 °C). After leaching, the electrodes active material contained in the metals decreased, while it was still significant in the graphite, as observed by scanning electron microscopy-energy dispersive spectrometry and x-ray powder diffraction. Even though the performed economic evaluation was a summarized outline it can be considered suitable to compare different leaching conditions and to determine the possible best combinations of factors that can optimize the profit response.

Keywords: Acid leaching; Economic evaluation; Lithium-ion batteries; Optimization.