Photocatalysis-Assisted One-Step Synthesis of Ferrous Pyrophosphate from Retired Lithium–Iron Phosphate Batteries: A Green Route to the Selective Synthesis of Anode Materials

As the service life of the most widely utilized lithium–iron phosphate (LFP) batteries is only 5–8 years, the demand for recycling retired LFP batteries is urgent globally due to the severe resource and environmental challenges they pose. However, traditional recycling strategies face high energy consumption and high pollution issues. Herein, we propose a lithium-leaching strategy using photocatalysis techniques; the residue is ferrous pyrophosphate instead of the commonly reported FePO4, and this unique selectively evolved residue can be directly applied as an anode for lithium-ion batteries. The electrochemical performance of this one-step synthesized ferrous pyrophosphate relies on the elaborate protection of the initial microstructure of LFP particles via dopamine hydrochloride, and the obtained ferrous pyrophosphate exhibits an initial discharge capacity of 963.7 mA h g–1 at 100 mA g–1, together with 300 stable cycles without any capacity decay. Meanwhile, it exhibits a boosted rate performance of 393.8 mA h g–1 at 1000 mA g–1. This study opens a new opportunity to recycle retired LFP with an environmentally friendly route and is expected to innovate the reuse methods for retired LFP batteries.