With the rapid development of portable electronic devices and electric vehicles, the production and demand of lithium-ion batteries (LIBs) have increased exponentially. Due to the limited life of LIBs, a huge amount of spent LIBs will inevitably be produced in the next 10~20 years. Efficient and clean recovery of spent LIBs is significant for resource recycling and environmental protection. In the recovery process, the cathode active material containing valuable metals must be separated efficiently from the Al foil collector. This procedure is a crucial link to reduce the difficulty of subsequent metal extraction and to achieve resource recovery. However, the organic binder polyvinylidene fluoride (PVDF), due to its strong adhesion and stability, has become a critical factor hindering the separation of cathode active materials. Currently, the methods for separating cathode active materials from Al foils can be classified into physical, thermal treatment, solvent dissolution, and electrochemical methods. The physical methods include mechanical crushing and grinding. The active materials separate when the cathode is exposed to mechanical forces in a shredder or impact/shear crusher. However, using mechanical crushing or conventional grinding methods are difficult to remove the organic binders on the active material surface only by mechanical force.Depending on the difference in thermal stability of the PVDF, Al foil and the active material, melting or degrading the PVDF binder on the surface of the cathode material can be used to separate the cathode active material. Direct calcination of PVDF is prone to pollutant emissions, and the pyrolysis process using a fully enclosed environment allows for better control and treatment of pollutant gases. Meanwhile, alkaline calcium oxide can accelerate the catalytic degradation of PVDF and enable the in-situ capture of inorganic fluoride. Apart from direct calcination / pyrolysis, new technology, such as molten salt-mediated treatment, can achieve the melting or degradation of PVDF in solid thermal media, detaching the cathode material from the Al foil and preventing the release of fluoride.Traditional strong polar organic solvents such as NMP, DMF, etc. can dissolve the binder by using the principle of similar solubility. However, the volatility and toxicity of these solvents are important obstacles to large-scale applications. The exploitation of organic solvents such as ethylene glycol and triethyl phosphate is expected to enable the replacement of highly volatile organic solvents. In addition, ionic liquids and deep eutectic solvents, as the new generation of green solvents, have shown potential for application in the separation of cathode materials. In addition to organic solvents, alkaline dissolution, oxidation by Fenton's reagent and electrochemical methods as representative of aqueous systems provide diverse options for the separation of cathode materials.Summary and prospectsIn summary, the current separation of spent LIBs cathode materials from the collector has made remarkable progress. In terms of overall effect, the current separation methods have successfully separated the cathode material from the collector Al foil, and the basic principles and process methods have been well investigated. However, analysis from a partial point of view, there are still some problems that need to be solved for different separation methods in terms of environment, economy and scale of use. Although the physical method has been widely used in industrial practice, problems such as low separation accuracy remain. The separation effect can be improved by the combined use of heat treatment method and physical method, i.e., the binder is removed by pyrolysis followed by crushing and sorting. This method achieves the separation of active materials from metal foils and substantially reduces the content of metal impurities in the active materials. However, this method is still difficult to achieve high-precision separation, and the development of more efficient physical separation methods and processes is still an important direction for future research. Compared with the physical method, the chemical method separates with higher precision. However, traditional chemical separation of active materials mostly uses toxic or volatile substances, with a high risk of secondary pollution. Fenton oxidation and supercritical fluid are green and environmentally friendly, but the high cost makes it difficult to industrialize and promote the application. The development of green, safe and low-cost solvents to achieve economic and efficient separation of active materials is another important direction that needs attention in the future.