Direct Recycling of Mixed-Oxide Cathodes: Balancing Cost, Performance and Environmental Trade-Offs

Area of Science:

• Materials Science
• Chemical Engineering
• Electrochemistry

Background:

• Relithiation is crucial for recycling spent lithium-ion battery cathodes.
• Various methods exist, but a comprehensive comparison is lacking.

Purpose of the Study:

• To compare five relithiation methods: solid-state relithiation (SSR), hydrothermal relithiation (Hydro), molten salt thermochemistry (MST), electrochemical (EC), and chemical (Chem).
• To evaluate these methods using techno-economic, electrochemical, and environmental/toxicological metrics.

Main Methods:

• Harmonized techno-economic analysis (Group I).
• Electrochemical performance evaluation (Group II).
• Environmental and toxicological assessment (Group III).

Main Results:

• SSR/Hydro excel in techno-economic metrics.
• MST and SSR show strong electrochemical recovery.
• EC has low energy use but higher lab-scale costs; Chem is competitive.
• CO2 emissions rank EC < Chem < MST < Hydro < SSR; Chem is most toxic.
• Chem leads in integrated performance (72.3 pts), followed by SSR, Hydro, MST, and EC (60-65 pts).

Conclusions:

• For Ni-rich cathodes, methods with a high-temperature step are transferable.
• Electrochemical (EC) and Chemical (Chem) methods are suitable for mild regeneration only.