• Reduction leaching with iron powder achieves 97% leaching rate of iron phosphate residue, significantly higher than direct leaching.
• Activation energy for reduction leaching is 12.71 kJ/mol, lower than 21.57 kJ/mol for direct leaching, indicating easier reaction.
• Reduction leaching reduces leaching time by half and acid consumption by 30% compared to direct leaching at the same efficiency.
• The study offers a sustainable and efficient method for recycling iron and phosphorus from spent LiFePO4 batteries, addressing environmental and resource concerns.