Cyclic redox strategy for sustainable recovery of lithium ions from spent lithium iron phosphate batteries

•Extraction of excess lithium ions using a small amount of chemical reagent.•No introduction of impurity cations.•The chemicals used in this program are inexpensive. The growth of spent lithium-ion batteries requires a green recycling method. This paper presents an innovative hydrometallurgical approach in light of redox flow batteries, which employed Fe3+/Fe2+ as regenerative redox mediator to selectively extract Li+ from LiFePO4. In contrast to the conventional method in which the oxidizer is disposable, the present scheme allows for the recycling of the oxidizer, which demonstrates the advantages of environmentally friendly, low cost and higher extraction rate, offering a novel approach to recycling spent batteries.