Recycling of electrode materials from spent lithium-ion power batteries via thermal and mechanical treatments.

ABSTRACT

This study developed a physical separation process that recovers active cathode materials from current collectors in spent lithium-ion power batteries (LIBs). The physical separation process, implemented via thermal and mechanical treatments, was examined based on cohesive zone models (CZMs) and verified by physical separation experiments. The most efficient condition was determined by optimising the key parameters (temperature and time) of selective heating. Among several mechanical separation methods, high-speed shearing best separates positive electrode materials into active cathode materials (LiFePO4) and current collectors (Al fragments). The separation effect was verified by computing the dissociation rate and microscopic observation of the separated materials. The feasibility and efficiency of the above process were assessed in a work-of-force analysis, flow field simulation, high-speed crushing experiment and material property analysis. The above analyses realised a feasible, efficient and environmentally friendly separation route without changing the chemical structure and properties of the electrode materials. Under non-high (energy-conserving) temperature conditions, the LiFePO4 dissociation rate stabilises at 80-85%. Under high-speed crushing, the LiFePO4 dissociation rate reaches 85% at 32,000-r/min crushing and a maximum shearing velocity of the blade edge v ≈ 500 m/s. This approach can effectively recycle electrode materials, gain valuable resources and can be used to recycle and utilise spent LIBs, thus addressing two grave issues - environmental pollution and resource wastage to achieve the sustainable development of LIBs and electric vehicle industry.