The commercialization of cost-effective and environmentally conscious battery recycling technologies has long been hindered by low material yields, structural degradation, and high energy demands. Now, researchers from Gachon University, Tsinghua University, and MIT have developed a new upcycling method that transforms medium-Ni cathodes from spent lithium-ion batteries into high-energy, single-crystalline Ni-rich cathodes—without the need for corrosive chemical treatments or destructive conversion to metal compounds.

Ni-rich layered cathodes, such as NCM811, are essential for next-generation electric vehicles (EVs) due to their high capacity and energy density. However, conventional recycling methods—pyrometallurgy and hydrometallurgy—are environmentally taxing, often destroying the original crystal structure and generating toxic waste. While direct upcycling methods have emerged as alternatives, they have struggled with inhomogeneous ion diffusion, rock-salt phase formation, and limited scalability.

To overcome these obstacles, the research team led by Professor Moonsu Yoon (Gachon University), Professor Yanhao Dong (Tsinghua University), and Professor Ju Li (MIT) introduced a quasi-liquid-phase engineering strategy using eutectic lithium salts (LiOH–LiNO3) and nickel nitrate (Ni(NO3)2·6H2O). Activated by planetary centrifugal mixing, this formulation locally melts via frictional heating, forming a transient liquid environment that enables uniform lithium and nickel redistribution across spent medium-Ni cathodes (NCM523) particles. This facilitates the suppression of resistive rock-salt phases and promotes the growth of robust single-crystalline structures.

The upcycled cathode materials (LiNi0.80Co0.08Mn0.12O2) achieved a discharge capacity of 198 mAh/g and an initial Coulombic efficiency of 87.3%. In practical pouch-cell tests with a 700 mAh capacity, the cells retained 88.1% capacity after 300 cycles at 1C, demonstrating exceptional structural integrity and long-term performance.

Professor Yoon said, “This work not only delivers a sustainable solution for cathode regeneration, but also reveals a new class of low-temperature, equipment-compatible upcycling chemistry,” and added, “We believe it sets a clear pathway toward scalable and environmentally friendly battery circularity.”

Morphological and structural evolution of spent NCM523 during the liquified-salts-assisted upcycling process.
Reprinted with permission. Energy & Environmental Science, DOI : 10.1039/D5EE01086A

[Reference] Yoon M. et al., (2025) “Upcycling spent medium-Ni cathodes via novel liquified salt sourcing”, Energy& Environmental Science, 10.1039/D5EE01086A

[Main Author] Moonsu Yoon (Gachon university, Republic of Korea), Yanhao Dong (Tsinghua univeristy, China), Ju Li (MIT, US)

* Contact : Prof. Moonsu Yoon (msyoon23@gachon.ac.kr)