Synthesis of LiFePO4 cathode materials from amorphous FePO4 precursor: Effects of Li/P molar ratio on crystal defect formation and electrochemical performance

As an excellent cathode material, lithium iron phosphate (LiFePO₄) has been widely used in commercial lithium-ion batteries (LIBs). However, the impact of synthetic conditions on LiFePO₄ cathode derived from amorphous iron phosphate (FePO₄) remains underexplored. In the present study, the effects of Li/P molar ratio on the crystallinity and electrochemical properties of LiFePO₄ were investigated in detail using FePO₄ as a precursor. When the Li/P molar ratio in LiFePO₄ was approximately 1, the material exhibited an excellent long-term cycling stability with a high capacity retention of 97 % after 500 cycles. In addition, multiple characterizations demonstrate that the higher molar ratio of the Li/P resulted in the higher concentration of defects in LiFePO₄ crystals, which not only reduced the reversible capacity but also compromised the structural stability, leading to a poor cyclic stability and quick capacity degradation. Therefore, such a work could provide a scientific insight for rational design and synthesis of high-performance LiFePO₄ cathodes from amorphous FePO₄ precursor.