Challenges in Recycling Spent Lithium-Ion Batteries: Spotlight on Polyvinylidene Fluoride Removal

In the recycling of retired lithium-ion batteries (LIBs), the cathode materials containing valuable metals should be first separated from the current collector aluminum foil to decrease the difficulty and complexity in the subsequent metal extraction. However, strong the binding force of organic binder polyvinylidene fluoride (PVDF) prevents effective separation of cathode materials and Al foil, thus affecting metal recycling. This paper reviews the composition, property, function, and binding mechanism of PVDF, and elaborates on the separation technologies of cathode material and Al foil (e.g., physical separation, solid-phase thermochemistry, solution chemistry, and solvent chemistry) as well as the corresponding reaction behavior and transformation mechanisms of PVDF. Due to the characteristic variation of the reaction systems, the dissolution, swelling, melting, and degradation processes and mechanisms of PVDF exhibit considerable differences, posing new challenges to efficient recycling of spent LIBs worldwide. It is critical to separate cathode materials and Al foil and recycle PVDF to reduce environmental risks from the recovery of retired LIBs resources. Developing fluorine-free alternative materials and solid-state electrolytes is a potential way to mitigate PVDF pollution in the recycling of spent LIBs in the EV era.

Automated summary

In the recycling of retired lithium-ion batteries (LIBs), the separation of cathode materials and aluminum foil is crucial for efficient metal recycling. However, the strong binding force of PVDF hinders their effective separation, leading to difficulties in metal extraction. This paper reviews the composition, properties, and binding mechanism of PVDF, as well as the separation technologies and reaction behavior of PVDF during the recycling process. Efficient separation of cathode materials and aluminum foil, along with the recycling of PVDF, is critical for reducing environmental risks. Developing fluorine-free alternative materials and solid-state electrolytes can help mitigate PVDF pollution in the recycling of LIBs in the EV era.