Direct regeneration of highly degraded LiNi0.6Co0.2Mn0.2O2 to high-performance single-crystalline cathodes

Abstract

The widespread popularization of electric vehicles and portable electronics gives rise to the concomitant surge of spent lithium-ion batteries (LIBs). Considering the resource shortage and environmental concerns, recycling degraded cathode materials is highly desirable to ensure the sustainable development of the whole LIBs industry. To this end, a facile LiBr-LiOH eutectic molten salt strategy is proposed for direct regeneration of highly degraded polycrystalline LiNi_0.6Co_0.2Mn_0.2O₂ (denoted as D-NCM622), which enables efficient renovation of the nonstoichiometric composition and damaged crystal structure in D-NCM622, including full Li-supplement, complete restoration from rock salt/spinel phases to the original layered structure, suppressive cation disorder, and reconstructed single-crystalline nature. Benefiting from these favorable structural characteristics, the regenerated cathodes (R-NCM622) exhibit significantly enhanced electrochemical performance relative to D-NCM622, delivering an initial discharge capacity of 174.0 mAh g⁻¹ at 0.2 C, capacity retention of 82.5% after 200 cycles at 0.5 C, and excellent rate performance (136.7 mAh g⁻¹ at 5 C), which is comparable to the fresh commercial NCM622 (C-NCM622). More significantly, the current regeneration route possesses the incomparable advantages in economic benefit and environmental impact compared to conventional recycling routes based on techno-economic analysis, ensuring sustainable recycling from highly degraded cathode materials.