The increased demand for Li-ion batteries has prompted the scientific community to improve recycling routes in order to reuse the valuable materials in batteries. After their end-of-life, the batteries are collected, discharged, and mechanically disintegrated, generating plastic and metallic streams that are recycled directly; this leaves behind a small particle size fraction known as black mass (BM). BM is composed mainly of graphite and Li-metal complex oxides. Pyrometallurgy is a route known for recycling of BM, in which identifying the BM’s behavior at high temperatures is essential. In this study, two types of BM are characterized in two fractions of 150–700 µm and smaller than 150 µm. The thermal behavior of the BM is studied with thermal analysis techniques. The analyses demonstrate that the mineralogical and morphological properties of the two fractions do not significantly differ, while the amounts of C and organic materials might vary. When the BM was thermally treated, the binders decomposed until a temperature of 500 ℃ was reached, where the volatilization of hydrocarbons was observed, although F mostly persisted in the BM. The Li-metal oxide was partially reduced to lower oxides and Li carbonate at ⁓ 600 ℃, and the main mass loss was caused by carbothermic reduction immediately thereafter. As the products of this process, metallic Co and Ni phases were formed, and part of the graphite remained unreacted. Regarding the Li behavior, it was observed that in the presence of Al, AlLiO2 is the most likely composition to form, and it changes to LiF by increasing the F concentration in the composition.

Pyrometallurgy is a popular industrial method that is employed in the recovery of valuable elements from black mass (BM), which is produced by pretreatment of Li-ion batteries. This method struggles with some downsides, such as the incineration of graphite and high energy consumption. In this study, the goal is to utilize graphite in the BM to produce a master alloy in an attempt to decrease the energy input requirement. To achieve this, metal oxides (Fe₂O₃ and CuO) are added to the BM to produce an Fe/Cu-based alloy containing Co/Ni as alloying elements. Mechanical activation is also employed to decrease the energy requirement and to increase the amount of metal oxide that can be reduced by the graphite in the BM. The results revealed that it is possible to produce the aforementioned alloys, the efficiency of which can be improved by applying mechanical activation. After 1 h of milling, the required heat flow for producing Fe- and Cu-based alloys is lowered for ⁓10 and ⁓25 kWh, respectively. Plus, the direct CO₂ emission decreases for 13-17% in the iron system and 43-46% in the copper system.

Li-ion batteries (LIBs) are widely used nowadays. Because of their limited lifetimes and resource constraints in manufacturing them, it is essential to develop effective recycling routes to recover their valuable elements. This study focuses on the pyrometallurgical recycling of black mass (BM) from a mixture of different LIBs. In this study, the high-temperature behavior of two types of mixed BM is initially examined. Subsequently, the effect of mechanical activation on the BM reduction kinetics is investigated. Finally, hematite is added to the BM to first be reduced by the excess graphite in the BM and second to form an Fe-based alloy containing Co and Ni. This study demonstrates that mechanical activation does not necessarily affect the kinetics of BM high-temperature behavior. Furthermore, it demonstrates that alloy-making by the addition of hematite is a successful method to simultaneously utilize the graphite in the BM and recover Co and Ni, regardless of the LIB type.

Today, Li-ion batteries (LIBs) play a vital role in reducing the consumption of fossil fuels. With the increasingproduction of LIBs, it is crucial to consider their recycling after reaching their end-of-life. Pyrometallurgy is a technique that can be employed for the recycling of LIBs, which deals with the formation of three phases: melt, slag, and gas. In-situ alloying by the addition of hematite to the LIB black mass was studied previously by the authors. The effect of slag composition in terms of CaO:SiO2 ratio on the aforementioned system in terms of the melting, slag/metal separation, and Li/F evaporation behavior has been investigated in this work. The CaO:SiO2 mass ratios of 0:100, 25:75, 50:50, 75:25, and 100:0 were tested in that system at a temperature of 1450 °C. Thermodynamic modeling with FactSage 8.0 supported the experimental work. From this qualitative study, it can be anticipated that by increasing the SiO2 amount, metallics coalesce more effectively, the probability of metal/slag separation increases, and Li evaporation is enhanced. The addition of CaO may result in the entrapment of Li within the Ca silicate structure and decrease its vapor partial pressure. Thermodynamic modeling revealed a consistent trend in the distribution of Li and F as the CaO:SiO2 ratio changed, suggesting the potential formation of gaseous compounds such as LiF.