Single-Source Lithium Phosphate Precursor Engineering for Sustainable and Supply-Chain-Resilient Lithium Iron Phosphate Cathodes.

Synthesis of lithium iron phosphate (LiFePO4, LFP), a dominant cathode material for lithium-ion batteries, typically relies on multi-precursor systems involving phosphoric acid, whose production is sulfuric-acid-intensive and associated with environmental burden and supply-chain volatility. Here, a greener single-source method is introduced using lithium phosphate (Li3PO4, LPO) as the sole Li-P precursor for hydrothermal LFP synthesis. Because LPO remains largely solid during hydrothermal processing, its physical characteristics directly influence LFP formation. Mechanistic analysis shows that the smaller particle size, finer crystallite structure and reduced agglomeration of self-synthesized LPO (Self-LPO) shorten diffusion distances and improve solid-liquid interfacial accessibility, promoting more homogeneous conversion, nucleation and crystal growth while limiting coalescence and lattice distortion during subsequent calcination. Consequently, LFP@C-Self-LPO delivers 150.9 mAh g-1 at 0.1 C and 89% capacity retention after 500 cycles at 5 C. A Si || LFP@C-Self-LPO full cell further achieves an initial energy density of 364 Wh kg-1 at 1 C. By linking single-source precursor design with reaction-structure evolution, electrochemical performance and supply-chain considerations, this method provides a simplified and more sustainable framework for LFP cathode manufacturing, with reduced chemical handling and compatibility with emerging LPO-recycling pathways.