Recycling of LiCoO2 cathode material from spent lithium ion batteries by ultrasonic enhanced leaching and one-step regeneration.

A novel process for recycling of spent LiCoO2 cathode materials has been developed. The novel process comprises an ultrasonic enhanced leaching and one-step regeneration of LiCoO2 materials with spray drying method. The ultrasonic is novelly applied for effectively improving leaching process of spent LiCoO2 materials in the system of DL-malic acid and H2O2. The leaching efficiencies of 98.13% for Li and 98.86% for Co were presented under the optimal condition of 1.5 mol/L DL-malic acid with 3 vol% H2O2, the solid/liquid ratio of 4 g/L, ultrasonic power of 95 W, temperature of 80 °C and leaching time of 25 min. Based on kinetic analysis, the ultrasonic enhanced leaching process is mainly controlled by the diffusion control model. Meanwhile, the product of Co(C4O5O5)2 formed on particles surface of spent LiCoO2 materials during ultrasonic enhanced leaching process, which is provided from reaction mechanism analysis of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Finally, the regenerated LiCoO2 materials are regenerated in one step by spray drying from leaching solution, which present good electrochemical performance.

Leaching Li from mixed cathode materials of spent lithium-ion batteries via carbon thermal reduction.

The use of a carbon thermal reduction roasting method to recover lithium resources from spent lithium-ion batteries (S-LIBs) provides an important opportunity for recycling S-LIBs. The preferential extraction of Li via reduction roasting has been widely studied; however, the extraction of Li from mixed cathode materials has been rarely reported. Herein, we propose a method based on carbon thermal reduction to preferentially extract Li from mixed cathode materials. It was confirmed that there are differences in carbon thermal reduction products at 700 °C-850 °C by the thermodynamic analysis of the carbon thermal reduction process. At the same time, the effects of factors such as roasting temperature, roasting time, and material ratio on Li leaching efficiency were investigated. The Li recovery rate reached 98.86% under the optimal conditions of holding at 750 °C for 4 h with a molar ratio of mixed cathode materials to graphite of 1 : 0.25. Recovered Li2CO3 can be directly used as a lithium source for the regeneration of cathode materials. This study will provide new opportunities for the efficient recycling of spent lithium-ion batteries (S-LIB) mixtures.

The auto-oxidative relithiation of spent cathode materials at low temperature environment for efficient and sustainable regeneration.

The reasonable recycling of spent lithium ions batteries is urgently required and beneficial to new energy industry development to approach the "carbon neutral" target. It is urgent to understanding the structural evolution of spent lack lithium cathode materials during direct regeneration technology with low temperatures condition to avoid deficiencies of complex operation in existing technology. Herein, a novel approach was developed for direct regeneration of spent LiCoO2 materials with a successful structural repair and electrochemical performance recovery, which are composed of auto-oxidative process followed by pre-treatment process of dismantling, soaking and sintering. The auto-oxidative system was composed of LiBr as lithium source and dimethyl sulfoxide as solvent and oxygen donor. The recycled LiCoO2 material shows significantly close to capacity retention of 90.79% than that of the commercial LiCoO2 material. Based on the structural evolution mechanism analysis, the novel approach is still expected to be applied into regeneration of other spent cathode materials and guide an efficient and sustainable direction for the recycling of spent lithium ions batteries.