Impact of residuals on recovered nickel-rich LiNi$_{1-x-y}$MnxCo$_y$O$_2$ cathodes for direct recycling and reuse

At present, industrial-scale recycling of lithium-ion batteries typically involves rather energy-intensive processes and toxic solvents to recover, in particular, the metallic elements from the positive electrode active material. These recovered metals subsequently serve as precursors for the synthesis of new electrode materials. One approach to reduce the energy and cost needed is the direct recycling of the electrode active materials. Herein, two recovery methods, namely thermal and solvent-based recovery, are investigated for single-crystalline Ni-rich LiNi$_{1-x-y}$Mn$_x$CoyO$_2$ (NMC) high-energy cathodes. The NMC obtained via the thermal recovery method exhibits poor performance due to the generation of HF and the degradation of the material. In contrast, the NMC obtained via the solvent-based method, utilizing dimethyl sulfoxide as a non-toxic solvent, demonstrates superior performance, with a reduction in capacity of only 1.5 % compared to pristine NMC. This comparative analysis highlights the critical role of the separation procedure and, particularly, the detrimental effect of any remaining fluorinated binder.