Supercritical CO2 technology for the treatment of End-of-Life Lithium ion batteries

Abstract

The Li-ion batteries (LIBs) penetration in the automotive market makes more urgent the boosting of zero-waste battery recycling. This can play a crucial role in developing a circular economy through the recovery of critical raw materials (CRMs), as well as non-metallic components back to use. In recent years, the recycling technologies for LIBs entered in a new stage focused on the development of i) advanced pre-treatment processes to separate all the valuable battery components, and ii) more sustainable metallurgical approaches. Compared to the common recycling processes, Supercritical Fluid (SCF) technology is environmentally benign, chiefly if CO2 is used as the SCF (scCO2). This review aims at providing an overview on the current progresses and the open challenges of SCF technology for the treatment of End-of-Life LIBs. The fundamentals of SCF technology process are discussed, providing the reader a brief overview of principles, operation procedures and instrumentation. Thereafter, the main applications in the field of batteries recycling are reviewed, including electrolyte recovery and high-rate extraction of critical metals from the cathode. Finally, a focus is given on the huge innovation potential of scCO2 to separate and reuse the fluorinated binder from the electrode. At present, the binder is burnt in the common recycling processes, leading to hazardous fluorinated gas emissions.