Lithium-ion batteries (LIBs) have been widely used as power supplies for portable electronic devices. Of late, the LIBs are used as the dominant energy storage system in electric vehicles (EVs) due to their high energy density and energy efficiency. As interest in environmental issues such as carbon reduction increases, the electric vehicle market is growing explosively, and LIB demand is increasing exponentially. The rapid increase in the size of the LIB market was expected, but it was underestimated and is expanding faster than expected. It was recently reported that the entire LIB chain could reach a market size of 4.7 TWh indicating a value of more than $400 billion in 2030.[1] The recycling of end-of-life batteries is essential to avoid Li supply shortages and stabilize the Li supply chain.

In this study, slag obtained after arc smelting process performed with LIBs and slag system of Al₂O₃-CaO-MnO-SiO₂ was used. LIBs contain valuable metals such as Co, Ni, Cu and Li. After the arc smelting process, Co, Ni and Cu were recovered by formation of metal alloy layer. On the other hand, Li was lost and included in the slag layer. The slag was characterized by x-ray diffraction analysis and it was confirmed that the slag consisted of LiAl_xSi_yO_z and CaAl_xSi_yO_z phases. To recover Li from slag, chlorine roasting was performed using chlorine donors of NaCl, CaCl₂ and mixtures of NaCl and CaCl₂ to investigate the effect of chlorine donor materials on the Li extraction efficiency. The powdered slag was mixed with chlorine donors with a Cl/Li molar ratio of 2:1. The slag containing chlorine donors was roasted at temperature range between 600 and 900 °C. The chemical composition and phase transformation of the slag before and after chlorine roasting have been characterized. In conclusion, the Li extraction efficiency was improved by optimizing the Li recovery process from the slag obtained after the arc smelting process using the LIB.

References

[1] McKinsey & Company, 2023, www.mckinsey.com