Recovery of metallic values from spent Li ion secondary batteries

Abstract

The possibility of recovering metallic values from end of life Li ion secondary batteries by a precipitation technique using ethanol was investigated. This work aimed to maximise the recovery of the reusable materials and thereby minimise the environmental impact resulting from end of life batteries. After digestion in sulphuric acid, copper was recovered with 96% recovery efficiency as copper sulphate (CuSO₄.3H₂O) with the addition of ethanol at a volume ratio of 3: 1. Cobalt was recovered in two steps. During the first step, 92% of the cobalt is recovered as CoSO₄ by the use of ethanol at a volume ratio of 3: 1. The ethyl alcohol removes water ligands from the Co²⁺ cation, and caused the precipitation of cobalt as cobalt sulphate monohydrate. In the second step, the remaining cobalt was precipitated as cobalt hydroxide (Co(OH)₂) by increasing the pH value up to 10 with the addition of lithium hydroxide (LiOH). Lithium, which remained in the solution, was then recovered as lithium sulphate (Li₂SO₄) with up to 90% recovery efficiency by the addition of ethanol at a 3: 1 volume ratio. Aluminium was recovered as aluminium hydroxide (Al(OH)₃) with 99% recovery efficiency. It was shown that metals could be precipitated separately by the ethanol/sulphate precipitation technique depending on their concentrations present in the solution. The proposed process proved to be conceptually straightforward.