New insights into the pre-treatment of spent LiFePO4 batteries for direct recycling purposes

Licentiate thesis, 2026

The rapid electrification of the transportation sector is increasing the volume of spent lithium iron phosphate (LFP) batteries, yet direct recycling of LFP cathode active material (CAM) remains underdeveloped, despite spent LFP batteries starting to enter the recycling market. Direct recycling rests on a reduced number of process steps and a low impurity content in the recovered CAM, making the pre-treatment chain a decisive factor for success. This work examined three successive pre-treatment stages for spent LFP modules from real-life mild hybrid applications: discharging, delamination of the cathode from its current collector, and removal of impurities by solvent washing, followed by relithiation to restore electrochemical performance. Salt brine discharging induced electrode corrosion, elevating Cu and Al impurity levels, whereas resistor-based discharging preserved CAM integrity better and produced no waste, making it the preferable option. Four delamination routes were compared: freeze-drying, ethylene glycol treatment, phytic acid treatment, and the novel Librixer technology. Freeze-drying showed the highest peeling efficiency (93%), while Librixer exhibited by far the lowest projected energy consumption and cost. All methods retained LiFePO4 except for phytic acid, which leached Li and yieled mostly FePO4. Acetic acid emerged as the greenest solvent wash, though it traded Li losses for Cu removal. Relithiation with lithium acetate successfully regenerated the CAM, but overlithiation, unsuitable particle morphology, and residual Cu impurities limited electrochemical performance. These findings outline more and less favorable pre-treatment strategies for direct LFP recycling and identify the impurity control measures required to regenerate battery-grade CAM.