Understanding and Controlling Structural Defects and Disordering in LiNi_0.5Mn_1.5O₄ Cathodes for Direct Recycling.

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Direct recycling of spent lithium-ion batteries (LIBs) faces challenges with cathode material stability across various chemistries.
• Relithiation treatments can induce defects and disorder (e.g., Li/Mn) in LiNi0.5Mn1.5O4 cathodes, hindering performance.

Purpose of the Study:

• To investigate microstructure evolution during LIB cathode relithiation.
• To develop a defect engineering strategy for improving the direct recycling of high-voltage spinel-type cathodes.
• To enhance lithium-ion diffusion and cycling stability in regenerated LIB cathodes.

Main Methods:

• Systematic investigation of microstructure evolution during relithiation.
• Defect engineering via twin boundaries and preferred grain orientation.
• Electrochemical performance testing (cycling stability, capacity retention).

Main Results:

• Observed induced defects and Li/Mn disordering in LiNi0.5Mn1.5O4 during recycling.
• Regenerated cathodes with engineered defects showed enhanced Li+ diffusion.
• Achieved high capacity retention: 97.4% after 100 cycles and 87.96% after 200 cycles at C/3.

Conclusions:

• Defect engineering effectively restores structural integrity and electrochemical performance of recycled LIB cathodes.
• This approach offers a viable pathway for the sustainable direct recycling of high-voltage spinel cathodes.
• Addresses key limitations in current LIB recycling methods, promoting next-generation battery sustainability.