Proof-of-Concept study of ion-exchange method for the recycling of LiFePO4 cathode

Authors: ZHANG, XIAOXIAO - University Of Wisconsin; Liu, Zengshe - Kevin; QU, DEYANG - University Of Wisconsin

Submitted to: Waste Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2022
Publication Date: 12/10/2022
Citation: Zhang, X., Liu, Z., Qu, D. 2022. Proof-of-Concept study of ion-exchange method for the recycling of LiFePO4 cathode. Waste Management. 157:1-7. https://doi.org/10.1016/j.wasman.2022.12.003.
DOI: https://doi.org/10.1016/j.wasman.2022.12.003

Interpretive Summary: To combat global climate change, numerous countries have pledged net-zero carbon dioxide emissions short- and long-term goals. Recently a critical step and strategy to reach these goals has been the advancement of electric transportation, especially electric vehicles (EVs) using lithium-ion batteries (LIBs) which have experienced rapid development. In terms of low cost, safety, and recycle life, lithium iron phosphate (LFP) batteries are most widely used. However, the recycling of battery materials is still a challenge to the industry and the environment. In this research, we report not only the recycling of lithium, but also conversion of LFP material into fertilizer containing nitrogen, phosphorus, and potassium elements by using an economically sustainable method (ion exchange). This technology advancement will benefit the development of future EVs as well as lessen the environmental impact of the LIBs.

Technical Abstract: Recycling spent lithium iron phosphate (LFP) cathodes in an economically sustainable way remains a great challenge due to their low-value elemental composition. Thus, both low-cost technology together with a high-value product are critical for the recovery of the LFP materials. In this study, the commercially mature ion-exchange (IX) method was explored to recover Li from LFP material for the first time. The feasibility of Li-H and Li-K IX reactions using strong and weak acid cation exchange resins was systematically investigated from the thermodynamic and kinetic perspectives. Different organic and inorganic acids were explored to obtain the feeding solutions. Oxalic acid leaching solution with mild pH value and low iron impurity were determined to be the optimal feeding solution for IX reaction. The kinetics of IX and regeneration reaction were fast, and the resins can be reused several times without loss of IX capacity. Along with the P element remaining in the leaching solution, the Li-K IX reaction delivered a potential product of multi-elemental fertilizer. This simple and economical technology provides a practical recycling strategy for the spent LFP batteries.