A recent study published in Scientific Reports explores a novel approach to lithium recovery from spent lithium-ion batteries (LIBs). Researchers combined carbothermal reduction with water leaching under atmospheric conditions, achieving a remarkable 95.7 % lithium recovery with 100 % selectivity from nickel-manganese-cobalt (NMC) batteries.
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Background
As the global electric vehicle (EV) market continues to expand, two types of LIBs dominate: NMC batteries, known for their high energy density and suitability for long-range EVs, and lithium iron phosphate (LFP) batteries, valued for their safety, stability, and cost-effectiveness.
With millions of EV batteries expected to reach the end of their life cycle in the coming years—potentially exceeding 11 million tons by 2030—efficient recycling methods are essential. Effective recovery of valuable materials like lithium is key to minimizing environmental impact and promoting a sustainable, circular economy.
Recycling efforts, however, face challenges due to the mixed nature of spent LIBs. NMC and LFP batteries have different compositions, complicating the recovery process. This study focuses on selectively extracting lithium from NMC battery black mass using atmospheric water leaching, addressing a critical issue in LIB recycling.
Methods
The researchers collected spent NMC-532 and LFP battery cathodes from local recycling sources. They extracted black mass—active black powder containing elements from both the cathodes and anodes—as the primary material for processing.
Carbothermal treatment was conducted on various black mass mixtures, ranging from pure NMC to a 50:50 NMC-LFP ratio, at temperatures between 750 °C and 950 °C. Heating rates of 5 °C, 10 °C, and 15 °C per minute were tested. After treatment, the black mass was subjected to water leaching to assess lithium recovery efficiency.
To analyze the process, the researchers examined elemental composition using inductively coupled plasma optical emission spectroscopy (ICP-OES). They identified phases and component compositions through X-ray diffraction (XRD) and studied surface morphology and elemental distribution with scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX).
Functional groups in the compounds were investigated using Raman spectroscopy, while thermogravimetric analysis (TGA) was conducted from 30 °C to 1200 °C to monitor heat and mass changes during carbothermal reduction.
Results and Discussion
The heating rate during the carbothermal process significantly influenced lithium recovery via water leaching. Specifically, lithium recovery decreased with increasing heating rate, the maximum being 92.06 ± 0.42 % at 5 °C/min heating rate. This was attributed to the disturbed uniformity of the reduction reaction at higher heating rates, which led to uneven temperature distribution within particles and the formation of poorly soluble residual lithium compounds.
The target temperature also influenced the efficacy of the carbothermal reduction, with lithium recovery decreasing with increasing temperature. Although TGA indicated enhanced metal reduction at higher temperatures, lithium recovery decreased as lithium got incorporated into the Ni-Co alloy phase formed at these temperatures. XRD results confirmed the presence of this alloy phase, which hindered extraction during leaching.
TGA revealed considerable mass changes during the carbothermal reduction of mixed LFP-NMC black mass, indicating potential reactions or phase/structural transformations in the solid materials. However, the lithium recovery decreased with the increasing proportion of LFP in the mixed black mass. This decline was more pronounced for carbothermal reduction at 950 °C.
Furthermore, variations in processing temperature had little impact on lithium recovery from LFP-NMC mixtures. This suggests that the primary challenge in carbothermal reduction of mixed battery black mass was not the operating conditions themselves but the chemical reactions between components, which led to the formation of compounds that were resistant to water leaching.
Conclusion
The study demonstrated that carbothermal reduction combined with atmospheric water leaching can effectively recover lithium from mixed NMC-LFP battery black mass. Under optimized conditions (950 °C, 15 °C/min heating rate, 2 hours), lithium recovery from pure NMC black mass reached 95.7 ± 0.31 % with 100 % selectivity, aided by the formation of water-soluble compounds such as LI2O and Li2CO3.
However, introducing an equal amount of LFP into the NMC black mass disrupted the process, reducing lithium recovery to 9.78 ± 0.44 %. This decline was attributed to the formation of water-insoluble Li3PO4 and the entrapment of lithium within Fe-Ni-Co and Ni-Co alloy matrices.
To address this challenge, sodium carbonate (Na3CO3) was added during the carbothermal reduction process to suppress Li3PO4 formation. This adjustment increased lithium recovery to 59.47 % while maintaining 100 % selectivity by stabilizing lithium as Li2CO3, a water-soluble compound. These findings suggest that modifying process conditions with carbonate additives could improve lithium recovery efficiency in practical LIB recycling applications.
Journal Reference
Perdana, I., et al. (2025). Lithium recovery from mixed spent LFP-NMC batteries through atmospheric water leaching. Scientific Reports. DOI: 10.1038/s41598-025-86542-6, https://www.nature.com/articles/s41598-025-86542-6
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