Novel regeneration strategy restores high-nickel lithium-ion battery cathodes for enhanced performance and sustainability

This new direct regeneration approach, employing a LiOH-LiNiO3-lithium salicylate (LSA) eutectic salt system, restores the structural integrity and electrochemical performance of spent cathodes, offering a promising solution to enhance the lifespan and sustainability of lithium-ion batteries (LIBs).

LIBs are integral to modern energy storage, particularly in electric vehicles (EVs), due to their high energy density and long lifespan. However, the average lifespan of LIBs is about 5–8 years, with millions of tons of retired batteries expected by 2030. These spent batteries contain valuable materials like lithium, nickel, and cobalt, which are critical for resource recovery. Traditional recycling methods, such as pyrometallurgy and hydrometallurgy, face challenges like high energy consumption, environmental pollution, and the loss of material structure. In contrast, direct regeneration restores cathode materials by repairing their structure and compensating for lithium loss, making it a more sustainable and efficient recycling solution. However, previous regeneration methods for high-nickel NCM811 cathodes have struggled with uneven lithium compensation and structural degradation.

A study (DOI:10.48130/een-0025-0004) published in Energy & Environment Nexus on 16 October 2025 by Yang Yang’s team, Huazhong University of Science and Technology, not only extends the lifespan of the material but also improves its energy density, making it suitable for reuse in new batteries.

To investigate the structural evolution of spent NCM811 cathodes during degradation and regeneration, X-ray diffraction (XRD) and inductively coupled plasma optical emission spectrometry (ICP-OES) were employed. XRD analysis revealed that the regenerated R-NCM811 exhibited a well-ordered layered structure, with clear diffraction peaks at the (003), (101), and (104) planes. In contrast, the degraded S-NCM811 showed weaker, broadened diffraction peaks and a NiO impurity phase, indicating significant structural degradation. ICP-OES results showed that S-NCM811 had a lower lithium-to-metal ratio, reflecting lithium loss, while R-NCM811 demonstrated effective lithium compensation, with a higher Li/(Ni⁺Co⁺Mn) ratio, confirming structural integrity restoration. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) images showed that S-NCM811 particles were fragmented and cracked due to lattice distortion, whereas R-NCM811 exhibited smoother particles with more uniform sizes, indicating effective ion exchange and phase reconstruction. The regeneration process successfully healed microcracks and transformed polycrystalline materials into single crystals. Electrochemical testing revealed that R-NCM811 had a significantly higher initial discharge capacity (196.0 mAh·g^–1) compared to S-NCM811 (105.7 mAh·g^–1). After 200 cycles, R-NCM811 retained 76.0% of its capacity, indicating improved cycling stability. Cyclic voltammetry (CV) and impedance spectroscopy further confirmed the enhanced lithium-ion diffusion and interface reaction kinetics in the regenerated material. The successful regeneration was attributed to the synergistic effect of the LSA eutectic salt system, which facilitated lithium compensation, eliminated the NiO rock salt phase, and improved the material's crystallinity, restoring its electrochemical performance and structural integrity.

This study presents a promising approach for the regeneration of high-nickel NCM811 cathodes, overcoming critical issues related to lithium loss, structural degradation, and performance decline in spent materials. The use of a LiOH-LiNiO₃-LSA eutectic salt system offers an efficient, sustainable solution to restore cathode materials, providing new opportunities for closed-loop recycling and the development of long-lasting, high-performance batteries. As this method advances towards industrial scale-up, it could play a pivotal role in meeting the growing demand for energy storage and reducing the environmental impact of spent batteries.

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References

DOI

10.48130/een-0025-0004

Original Source URL

https://doi.org/10.48130/een-0025-0004

Funding information

The authors acknowledge research project 52576210 supported by National Natural Science Foundation of China.

About Energy & Environment Nexus

Energy & Environment Nexus is a multidisciplinary journal for communicating advances in the science, technology and engineering of energy, environment and their Nexus.