Surface Segregation-Assisted Direct Regeneration of Spent Layer Cathodes.

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Chemistry

Background:

• Spent lithium-ion battery cathodes pose environmental and economic challenges.
• Direct regeneration is hindered by the inert rock-salt phase in degraded cathode materials.
• Efficient lithium replenishment and phase reconstruction are crucial for effective regeneration.

Purpose of the Study:

• To develop a novel segregation-assisted regeneration strategy for spent cathode materials.
• To overcome the limitations of the inert rock-salt phase in direct regeneration.
• To enhance lithium-ion diffusion, structural reconstruction, and stability of regenerated cathodes.

Main Methods:

• Introduced high-valence tungsten (W6+) into the regeneration process of spent LiNi0.5Co0.2Mn0.3O2 (NCM523) cathodes.
• Leveraged segregation behavior of W6+ to regulate reaction thermodynamics.
• Induced in situ transformation of the NiO-type rock-salt phase.

Main Results:

• The strategy successfully facilitated the in situ transformation of the rock-salt phase into Li-W-Ni-O compounds and Li2WO4.
• Regenerated NCM523 cathodes exhibited a high reversible capacity (150 mAh g-1 at 0.5 C) and excellent cycling stability (83% capacity retention after 800 cycles).
• The approach demonstrated broad applicability to other degraded layered cathode materials (e.g., NCM622, NCM811).

Conclusions:

• The segregation-assisted regeneration strategy offers a scalable, energy-efficient, and sustainable route for recycling spent lithium-ion battery cathodes.
• This method effectively addresses the challenges posed by the inert rock-salt phase, improving regeneration efficiency.
• The study provides a promising pathway for advancing circular economy principles in battery technology.