Ozone selectively and green recovers lithium ions from lithium iron phosphate powder

Abstract: As lithium iron phosphate cathode materials do not contain high-value metals other than lithium, a balance needs to be struck between recycling efficiency and economic benefits in the recycling and utilization of used lithium iron phosphate cathode materials. Here, we describe a selective recovery process that can achieve economically efficient recovery and an acceptable lithium leaching rate. Selective recovery of lithium ions can be achieved by adjusting the concentration of acid and the dosage of oxidant. Iron is retained in the leaching residue in the form of iron phosphate and is easy to recycle and reuse. The influences of factors such as acid concentration, acid dosage, oxidant dosage and reaction temperature on the leaching of lithium and iron were comprehensively discussed, and the mechanism of selective leaching was clarified. This process significantly reduces the costs of processing equipment and chemicals. This increases the potential industrial applications of the process and makes the green and efficient recycling of used lithium iron phosphate cathode materials possible in the future.

2.1 Materials

The LFP powder with the main element contents (38.05wt%Fe and 4.66wt%Li) was purchased from Huawei Ruico Chemical Co., LTD., a limited company. HCl (36-38% by weight), NaOH and Na2CO3 were purchased from Beijing Chemical Plant (Beijing, China). Produce ozone of the required concentration from pure oxygen using the 3S-T10 ozone generator provided by Tonglin Technology Co., LTD. (Beijing, China).

2.2 Selective leaching of lithium

Put the powder and HCl (a total of 8g) into a 250mL three-necked flask and add ozone to the solution.

Using oxygen as the gas source, the output ozone concentration is adjusted by regulating the power of the ozone generator and is monitored by an ozone concentration analyzer (3S-J5000). Ozone is fully in contact with the leachate through titanium alloy aeration heads (with pore diameters of 1-2μm), and the temperature during the reaction process is controlled by the circulating water machine (SHBIII). The reaction was carried out at 20°C for 60 minutes.

The ozone equipment models used in this experiment are: 3S-T10 ozone generator and 3S-J5000 ozone detector.

Highly selective and green recovery of lithium ions from lithium iron phosphate powders with ozone

Research Article

Published: 05 March 2023

Volume 17, pages 749–758, (2023)