Efficient Electrochemical Recovery of Phosphate from Phosphogypsum Leachate for Lithium-Ion Battery Cathode Application

As an essential and eutrophication element, aquatic phosphorus (P) must be fine-controlled for both environmental protection and resource recovery. Traditional P recovery heavily relies on adsorption and precipitation. Herein, we report a sustainable electrochemical Faradaic process for efficient phosphate recovery from phosphogypsum (PG) leachate, yielding high-purity Fe 3 (PO 4 ) 2 ·8H 2 O, a valuable precursor for lithium-ion battery (LIB) cathodes. Leveraging the low solubility of Fe 3 (PO 4 ) 2 ·8H 2 O (p K sp ≈ 36) and stringent control of dissolved oxygen (DO) levels and pH (below 9), a P recovery efficiency of up to 99.3% with high selectivity has been achieved from undiluted leachate with an iron sacrificial anode. The residue P concentration down to 3.9 mg/L in effluent meets the discharge standards of China’s Emission Standards for Water Pollutants in the phosphate fertilizer industry (total phosphorus <10 mg/L). The recovered Fe 3 (PO 4 ) 2 ·8H 2 O is used to fabricate the LiFePO 4 /C electrode for LIB application via a solid-state chemistry synthesis process, which exhibits a high discharge capacity (52.36–56.88 mAh/g), demonstrating the high-quality and potential of resource utilization of the recovered phosphate material for LIB cathode fabrication. This work demonstrates a novel, high-value pathway for sustainable phosphate recovery from PG leachate, promoting P resource management through a “waste-to-resource” strategy.