All-dry upcycling of used cathodes to single-crystal LiNi0.8Mn0.1Co0.1O2 for Lithium-ion batteries

The growing demand for lithium-ion batteries (LIBs) has resulted in a rise in the production and disposal of LiNi x Mn y Co z O 2 (x + y + z = 1) (NMC) cathodes, creating significant environmental and economic challenges. Effective recycling or upcycling of NMC cathodes is crucial to address these concerns and maintain the supply chain for essential materials. Herein, we report an all-dry upcycling method, directly converting used cathodes including LiCoO 2 (LCO), LiMn 2 O 4 (LMO), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NMC622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NMC811), and their mixtures, to single-crystal NMC811. Phase-pure NMC811 with low levels of impurities were upcycled from all of previously mentioned used cathodes. However, it was found that the crystal structure, homogeneity, and electrochemical performance of the NMC811 product depended on the used cathode material employed in its synthesis. Of these, the single-crystal NMC811 upcycled from used LCO had the highest performance with 207.09 mAh/g (at C/20) initial discharge capacity, 89.71 % initial coulombic efficiency and improved cycling performance compared to commercial NMC811. Our study presents a practical approach for cost-effective upcycling in the sustainable development of NMC batteries, paving the way for the recycling and upcycling of next generation LIBs. • All-dry method directly upcycles used cathodes into single-crystal NMC811 • Electrochemical performance of upcycled NMC811 depends on the type of used cathode • Upcycled NMC811 from LCO exhibits a reversible capacity of 207.09 mAh/g • This work enables practical upcycling for sustainable Li-ion batteries