Recovery of cathode materials from spent lithium-ion batteries using eutectic system of lithium compounds

Abstract

The cathode material is the focus of end-of-life lithium-ion battery recycling due to its high value. Cathode-to-cathode direct recycling avoids the need to change the cathode material to other metal forms, which could have significant economic and environmental advantages. A process that separates the cathode layer from current collector and recovers the active cathode materials is highly desirable as this facilitates the following regeneration step. In the present work, eutectic mixtures of lithium compounds are studies as an efficient and environmentally friendly approach for the separation and recovery of active cathode materials. Three commonly used inorganic lithium compounds i.e. LiCl, LiNO3, and LiOH, and their binary eutectic systems are investigated. It is found that LiOH-LiNO3 eutectic system has the highest peel-off efficiency. At temperature of 260 °C with 30 min holding time and salts/cathode electrode mass ratio of 10:1, up to 98.3% of cathode active materials can be recovered. The recovered cathode materials show minimal change and destruction on chemical composition, crystal structure, and morphology. Results suggest that LiOH-LiNO3 eutectic system can facilitate the decomposition of polyvinylidene fluoride binder and capture the HF released. The process based on eutectic systems of lithium compounds provides an alternative binder removal approach to organic solvents, and offers re-lithiation benefit without introducing impurities. It has the potential to promote direct recycling and sustainable recycling of spent lithium-ion batteries.