Direct hydrothermal regeneration and high value-added utilization of spent lithium iron phosphate for priority...

To address the global lithium shortage, direct regeneration of degraded cathodes via lattice reconstruction offers an eco-efficient strategy for recycling spent lithium-ion batteries (LIBs). However, industrial adoption is hindered by residual defects and insufficient lithium replenishment. Here, we propose a groundbreaking high-value reuse pathway, repurposing regenerated lithium iron phosphate (LFP) as an acid-stable adsorbent for priority lithium extraction from acidic leachate. Thermodynamic and electrochemical analyses suggested the stronger reductant facilitate the lattice reconstruction. The regenerated LFP, processed via a 2-hour hydrothermal repair at 220 °C using ascorbic acid, exhibited an exceptional lithium extraction capacity of 38.5 mg/g without electrode dissolution, selectively reducing residual lithium to < 20 ppm. By simultaneously enabling high-value utilization of spent LFP and priority lithium extraction, this paradigm bridges economic viability with circular economy principles, offering a blueprint for upcycling spent LIB materials.