Evolution fate of battery chemistry during efficient discharging processing of spent lithium-ion batteries

Residual electricity in spent lithium-ion batteries (LIBs) may cause safety issues during their dismantling and shredding in pretreatment processes. However, the migration and transformation of pollutants generated from spent LIBs during discharging were rarely reported, which is critical for prevention of pollution risk and facilitation of discharging efficiency. Herein, this work is focused on the evolution fate of battery chemistry during discharging processing. Here, migration of metal ions inside battery, galvanic corrosion on surface of battery and chemical evolution outside battery were investigated to attain the comprehensive understanding of discharging process. Firstly, efficient and complete discharging can be achieved using 5 wt% CuSO₄ as discharging medium, which mainly drive the migration of Li, instead of transition metals, from anode to cathode, resulting in enrichment of Li in cathode material. Besides, different degrees of galvanic corrosion phenomena on surface of spent LIBs can be discovered in different electrolyte solutions, involving with the corrosion of Al or Fe shells and resulting in the leakage of organic electrolytes inside battery into electrolyte solution. The detailed characterization results of the composition of solute indicate that hydroxide precipitates liberated from corroded shell and organic pollutants are their main existence states.