Measurements for refractory protection in pyrometallurgical recycling of lithium-ion batteries

Abstract

Recycling lithium-ion batteries (LIB) has become a key priority within the European Union's resource strategy, inducing a regulatory framework with ambitious recycling targets. Currently, no recycling technology meets these targets while remaining economically viable. The InduRed reactor, with its innovative pyrometallurgical approach via carbothermic reduction, presents a potential solution. A critical challenge, however, is the crucible's performance in the highly corrosive environment of aggressive melts and reducing gases. To address this, two protective measurements for a magnesium-oxide (MgO) crucible were investigated: one involved applying a thin graphite coating to minimize lithium diffusion, while the other utilized varying sizes of graphite cubes to create a protective temperature gradient. In addition, this study included the simulation of temperature distribution within the crucible using the OpenFOAM multi-region framework as a reason for the high impact of temperature on several different chemical and physical phenomena within the recycling process. Experimental findings show minimal lithium diffusion and corrosion in the graphite-coated crucible, with transfer coefficients above 90 % for all elements and up to 99 % for lithium. As revealed by Micro XRF cross-sectional analysis, the crucible with varying susceptor material sizes showed no contact between the input material and the refractory. This configuration can effectively act as a thermal and physical shield, providing an optimal barrier that prevents corrosion and diffusion effects at the crucible wall. This study demonstrates the potential of combining coatings and varied susceptor sizes for crucible protection, offering promising prospects for the InduRed reactor in future industrial applications.