I2I Phase I: Optimization of selective lithium recovery from spent lithium iron phosphate batteries with a green and environmentally responsible process

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Lithium iron phosphate (LFP) batteries are among the lithium-ion batteries (LIBs) that have the lowest production cost among almost all lithium-ion batteries and have excellent performance. Unlike other types of LIBs, LFP battery manufacturing does not require any cobalt, nickel, or manganese, which are among the expensive ingredients of LIBs manufacturing. Therefore the manufacturing cost of these LFP batteries is significantly, often 50%, less than the other types of LIBs. The lower contained metal value within LFP batteries makes their recycling economically unattractive, particularly because the cost of reagents used in the recycling process exceeds the value of the metals (i.e. mostly lithium) recovered from the LFP batteries.This project further develops a process that has been designed to selectively leach lithium from shredded LFP batteries, while leaving behind iron and phosphorous. In other words, the process is designed to recover only the valuable metal, i.e. lithium, from the LFP batteries, thus minimizing the energy, water, and reagent costs of the process. The shredded LFP batteries are leached in a water-formic acid-hydrogen peroxide system, where the concentration of formic acid is designed to be around 1 M, and hydrogen peroxide is added as an oxidant in the range of 1 to 5 wt%. The lithium from the LFP batteries is then recovered into the leach solution as lithium formate. Subsequently, the lithium-rich solution is separated from the solid residues. The solution carries mostly lithium and an insignificant amount of iron as an impurity, often in the low mg/L Fe range. After a pH adjustment for iron removal, the process water is ready for crystallization of high-grade and high-quality lithium phosphate crystals, with a grade above 99.5% Li3PO4.The process is developed to use environmentally friendly reagents and is a closed-loop process, producing no wastewater; therefore, the process can be applied in the vicinity of cities, where spent batteries are available.