Organic Ion‐Mediated Electrostatic Shielding Facilitates Membrane‐Free Electrochemical Hydrogen Production Coupling with LiFePO ₄ Recycling

Abstract

Abstract Electrolytic water splitting is a cornerstone technology for sustainable hydrogen (H 2 ) production. However, conventional methods face substantial challenges due to the slow kinetics of the oxygen evolution reaction (OER) and limitations imposed by ion‐exchange membranes, highlighting the need for innovative approaches. This study introduces a novel, membrane‐free electrolysis system that synergistically combines hydrogen generation with the recycling of spent lithium iron phosphate (LFP) batteries. Central to this system is the redox cycling of 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (4‐HO‐TEMPO), which facilitates electron transfer from LFP. To mitigate parasitic reactions in the absence of a membrane, an electrostatic shielding mechanism is implemented through the addition of polyquaternium‐7 (PQ‐7) to the electrolyte. This strategy effectively suppresses the unwanted reduction of redox‐active species by electrostatically repelling them from the electrode surface, as evidenced by rotating disk electrode and electrochemical impedance spectroscopy analyses. The proposed system achieves a remarkable hydrogen faradic efficiency of 92.4% and facilitates lithium ion recycling at a rate of 54.45 mmol L − 1 h − 1 under a current density of 100 mA cm − 2 . Our work presents a straightforward yet effective strategy for membrane‐free water electrolysis integrated with the sustainable recycling of spent LFP batteries through interfacial microenvironment control.