Important breakthrough in recycling of used lithium-ion batteries

On the 10th, the reporter learned from the School of Metallurgy and Energy Engineering of Kunming University of Science and Technology that the team of Professor Hua Yixin of the school has made important research progress in the field of recycling waste lithium-ion batteries with low eutectic solvents, which not only provides new ideas for the effective recycling of waste batteries, but also injects strong impetus into the sustainable development of the global lithium-ion battery market. The relevant research results were published in the international journal "e Science".

随着全球锂离子电池市场的快速增长，废旧电池的处理问题日益凸显。废旧电池中蕴含的有价金属如锂、钴等若能得到有效回收，不仅能缓解原材料枯竭的压力，还能显著降低环境污染。然而，传统的回收方法存在诸多难题，如锂在水溶液中难以沉淀、需添加多种沉淀剂回收过渡金属等。

Research diagram. Image provided by Kunming University of Science and Technology

To this end, Professor Hua Yixin and Associate Professor Ru Juanjian of Kunming University of Science and Technology have proposed an innovative strategy based on water balance to regulate the competitive coordination of ions in low eutectic solvents. This strategy achieves dual recycling of material recycling and solvent recycling by precisely controlling the water content in the solvent, effectively improving the recovery efficiency of valuable metals in waste batteries.

It is worth mentioning that the team has achieved the first preferential extraction of lithium and precise separation of cobalt in a low eutectic solvent. This breakthrough is due to the unique advantages of the choline chloride-oxalic acid-water low eutectic solvent, whose low viscosity, high solubility and selective precipitation of lithium-containing compounds make the preferential extraction of lithium possible. More importantly, no reducing agent or precipitant is required in the entire process, which greatly reduces the recycling cost and environmental risks.

In addition, the team also systematically analyzed for the first time the regulatory mechanism of water content on ion competitive coordination in low eutectic solvents. Through molecular dynamics simulation, the effects of water content and leaching temperature on ion competitive coordination were revealed, and the preferential precipitation of lithium and the precise separation mechanism of cobalt were further clarified. This achievement not only provides theoretical support for the recovery of valuable metals in waste batteries, but also provides a reference for the recovery of other types of battery materials.

At present, this innovative strategy has been successfully applied to the recycling of a variety of lithium-ion battery cathode materials, opening up a new path for the resource utilization of waste battery materials. "We have reason to believe that with the continuous promotion and application of new technologies in the future, waste batteries will no longer be 'waste', but a valuable resource, contributing to green and sustainable development." Hua Yixin said.