Efficient Non-Invasive Rejuvenation of Spent Lithium Iron Phosphate Batteries Through Controlled Overdischarge

Recycling lithium iron phosphate (LFP) batteries presents critical economic and environmental challenges because of their low metal value and high energy intensity of conventional metallurgical processes. While direct recycling methods offer a pathway for lithium replenishment, they are often hindered by stringent impurity controls and complex operating conditions that limit scalability. Here, we introduce a controlled overdischarge (COD) protocol as a non-invasive strategy to rejuvenate spent LFP (S-LFP) batteries. COD selectively decomposes the solid-electrolyte interphase, releasing trapped Li⁺ and reducing Li/Fe antisite defects while simultaneously suppressing copper dissolution. The COD protocol recovers 9.56% of lost capacity and extends lifespan by over 200 cycles. Furthermore, compared to metallurgical recycling, this method markedly lowers greenhouse gas emissions to 168 g kg^-1 and energy consumption to 3 MJ kg^-1 of feedstock. These findings highlight COD as a sustainable and scalable alternative for S-LFP battery recycling.