Cost-Effective Synthesis of Triphylite-NaFePO4 Cathode: A Zero-Waste Process

Triphylite-NaFePO4 attracts considerable attention as a cathode material for sodium-ion batteries due to its theoretical capacity (154 mAh/g), sharing also the excellent properties of the analogous triphylite-LiFePO4 used in commercial lithium-ion batteries. In this work, triphylite-NaFePO4 is synthesized from triphylite-LiFePO4 by a low-cost, eco-friendly method, enabling the recovery and subsequent reuse of lithium. NaFePO4 was evaluated as a cathode material in half-cells, exhibiting an initial discharge capacity of 132 mAh/g and good capacity retention (115 mAh/g and ∼100% of Coulombic efficiency after 50 cycles; 101 mAh/g and ∼100% of Coulombic efficiency after 200 cycles). This research confirms that the triphylite-NaFePO4 cathode material is an attractive candidate for sodium-ion batteries, with potential for future commercialization.