Separation of the cathode materials from the Al foil in spent lithium-ion batteries by cryogenic grinding

Abstract

An environmentally friendly technology of cryogenic grinding for recovering cathode materials from spent lithium-ion batteries was has been investigated in this paper. Differential Scanning Calorimeter was used to test the glass transition temperature of the organic binder. Advanced analysis techniques, a microcomputer-controlled electronic universal material-testing machine, a low-temperature impact testing machine, scanning electron microscopy and high-resolution 3 Dimension-X-ray microscopy, were utilized to analyze the effect of low temperature on the mechanical properties and morphology of cathode. Results show that the yield strength, tensile strength and impact strength of the current collector is significantly increased at low temperature, that the glass transition temperature of the organic binder is approximately 235 K. Low temperature enhances the strength of the current collector and causes the organic binder to fail. Therefore, cryogenic grinding could realize the selective grinding of the cathode and significantly improve the peel-off of the electrode materials. The peel-off efficiency of cathode materials was improved from 25.03% to 87.29% at the optimum conditions of low temperature pretreatment for 5 min and cryogenic grinding for 30 s. The experiments demonstrate that the cryogenic grinding can obviously facilitate the efficient recovery of cathode materials, revealing a great application prospective for the recycling of spent lithium-ion batteries.

Keywords: Cryogenic grinding; Peel-off efficiency; Recovering; Spent lithium-ion batteries.