The rapid expansion of consumer electronics, electric vehicles, and stationary energy storage systems has led to a continuous increase in both production waste and end-of-life lithium-ion batteries (LIBs). Efficient recycling is crucial to minimize environmental impacts and ensure the sustainable supply of critical raw materials. Among various recycling strategies, direct recycling has emerged as a promising approach, as it preserves materials in their original structure and avoids conventional “downcycling” into precursor compounds.[1] Most research to date on direct recycling of end-of-life NMC batteries has focused primarily on evaluating the regeneration conditions for degraded NMC cathode materials.[2] NMC regeneration typically involves relithiation and structural restoration to recover a material with properties comparable to fresh NMC. However, this approach faces a major limitation: by the time batteries reach their end of life – often years after production – the NMC chemistries may already be technologically outdated. To overcome this challenge, upcycling of end-of-life NMC has recently gained attention as a more industry-relevant strategy. Instead of restoring outdated NMC compositions, upcycling aims to convert them into next-generation NMC materials, thereby aligning recycling efforts with the latest developments in battery technology and market needs.
In this study, the upcycling of NMC532 to a nickel-rich NMC (similar to NMC811 stoichiometry) was investigated using a model system. The impact of annealing temperature and annealing time on electrochemical performance was systematically examined, and optimized conditions were transferred to end-of-life (EoL) NMC material. However, direct parameter transfer proved inadequate, as impurities and particle size variations significantly influenced the upcycling results. Initial results indicate that incorporating additional pre- and post-processing can further improve the upcycling results for EoL NMC.

References
[1] A. Prazanová, V. Knap, D.-I. Stroe, Energies, 2022, 15, 1086.
[2] G. Wei et al., iScience, 2023, 26, 107676.

The authors acknowledge funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No. 101069865. The output reflects the views only of the author(s), and the European Commission cannot be held responsible for any use which may be made of the information contained therein.