Återvinning av metaller från litiumjonbatterier

Sammanfattning

As a result of the rapid transition to a more sustainable society, with lithium-ion batteriesat its core, the development of efficient and sustainable recycling methods is of paramountimportance. The lithium iron phosphate (LiFePO4, LFP) battery is one of many differentbattery chemistries in use today, and it has become increasingly important due to its longlife cycle and its excellent thermal stability. As large quantities of these batteries are beingproduced, a growing volume of spent batteries are entering the waste stream, where their highmetal concentration makes them both a valuable resource as well as an environmental hazard.This work investigates the leaching step of the hydrometallurgical method, which is one of manymethods used for the recycling of critical metals from spent lithiumionbatteries. A comparisonbetween an organic acid (acetic acid, CH3COOH) and an inorganic acid (nitric acid, HNO3)was made in order to compare the efficieny as well as the selectivity of each acid. Furthermore,the impact of temperature was also analyzed. The use of Inductively Coupled Plasma OpticalEmission Specotrometry (ICP-OES) was implemented in order to analyze the leachates and thedigested residues, while the precipitate that formed in the acetic acid solutions was analyzedusing X-ray diffraction (XRD).The results showed that acetic acid achieved a lower leaching efficiency than that of nitricacid, but provided a higher selectivity, with the dissolution of iron and phosphorus remainingrelatively low. Nitric acid achieved a high leaching efficiency for all metals, making it thestronger solvent at the cost of lithium-selectivity. Following each experiment with acetic acidat room temperature (25°C), a precipitate formed in the solution. Further analysis using XRDand ICP-OES indicated that the precipitate consisted mainly of iron-phosphate, suggesting thelow dissolution of iron and phosphorus might be connected to precipitation reactions.This work demonstrates the differing behaviors of each acid and the fact that the choice of acidgreatly impacts overall leaching efficiency and selectivity.