Influence of Impurities on the High-Temperature Behavior of the Lithium-Ion Battery Cathode Material NMC under Reducing Conditions for Use in the InduRed Reactor Concept

In terms of an efficient circular economy in the field of the steadily increasing use of lithium-ion batteries, sustainable recycling methods are of fundamental importance. Therefore, the Chair of Thermal Processing Technology at Montanuniversitaet Leoben has developed the so-called InduRed reactor, a carbo-thermal concept to recover valuable metals from this waste stream. For optimization and further development of this technology, it is essential to have a sound knowledge of the cathode materials' behavior in combination with various impurities in the high-temperature range under reducing conditions. Detailed experiments were carried out in a heating microscope at temperatures up to 1620°C and argon purge. Aluminum from the electrode conductor foils and an excessive proportion of graphite from the anode were identified as the impurities with the most significant negative influence on the process. An optimum melting behavior was found during the tests at an admixture of 10 wt. % C and 1.95 wt. % Al to the cathode material NMC622 (LiNi0.6Mn0.2Co0.2O2).